Buffer Overflow
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
How It Works
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions. This overwrites whatever data or code exists there, corrupting program state and potentially giving attackers control over execution flow.
Stack-based overflows are the most common variant. When a function allocates a fixed-size buffer on the stack and then copies user-controlled input without proper bounds checking, attackers can overflow past the buffer to overwrite the function's return address. When the function completes, instead of returning to legitimate code, execution jumps to attacker-specified memory containing malicious shellcode. Heap-based overflows work differently—they corrupt heap metadata like chunk size fields or free list pointers, leading to arbitrary memory writes when the allocator processes the corrupted structures.
Modern exploitation bypasses defensive mechanisms through techniques like Return-Oriented Programming (ROP), which chains together existing code snippets to avoid non-executable memory protections. Attackers may also use heap spraying to reliably position shellcode at predictable addresses, defeating address randomization.
Impact
- Remote code execution — attacker gains ability to run arbitrary commands with the privileges of the vulnerable process
- Privilege escalation — exploiting kernel or setuid program overflows to gain root/SYSTEM access
- Denial of service — crashes and memory corruption that render systems unusable
- Information disclosure — reading sensitive data from adjacent memory regions that should be inaccessible
- Authentication bypass — overwriting security-critical variables like permission flags or user IDs
Real-World Examples
Fortinet FortiOS suffered a critical buffer overflow (CVE-2025-32756) that allowed unauthenticated remote attackers to execute code as root on firewalls and VPN gateways. Attackers actively exploited this to compromise enterprise network perimeters before patches were available.
The Slammer worm from 2003 exploited a stack overflow in Microsoft SQL Server, spreading to 75,000 hosts in ten minutes by sending a single malformed UDP packet that overwrote the return address with shellcode. No authentication was required.
OpenSSH historically contained a heap overflow in challenge-response authentication that allowed pre-authentication remote root compromise on Unix systems, demonstrating how memory corruption in privileged network services creates maximum impact scenarios.
Mitigation
- Memory-safe languages — Rust, Go, and modern managed languages prevent buffer overflows by design through automatic bounds checking
- Stack canaries — random values placed before return addresses that detect corruption before control transfer
- Address Space Layout Randomization (ASLR) — randomizes memory locations making exploitation less reliable
- Data Execution Prevention (DEP/NX) — marks memory regions as non-executable, preventing direct shellcode execution
- Bounds checking — validate input sizes before copying, use safe functions like
strncpyinstead ofstrcpy - Fuzzing and static analysis — automated testing to discover overflows before deployment
Recent CVEs (5405)
A vulnerability was found in PCMan FTP Server 2.0.7. Rated medium severity (CVSS 6.9), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
MicroDicom DICOM Viewer is vulnerable to an out-of-bounds read which may allow an attacker to cause memory corruption within the application. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
MicroDicom DICOM Viewer is vulnerable to an out-of-bounds write which may allow an attacker to execute arbitrary code. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A stack corruption vulnerability exists in the Linux kernel's ethtool CMIS CDB module due to incorrect buffer size calculation in the ethtool_cmis_module_poll() function. The vulnerability affects Linux kernel versions across multiple releases including 6.15-rc1 and 6.15-rc2, and can be triggered by local users with low privileges to cause a kernel panic and denial of service. A patch is available from the Linux kernel maintainers, and the EPSS score of 0.05% indicates low real-world exploitation probability despite the high CVSS score.
In the Linux kernel, the following vulnerability has been resolved: isofs: Prevent the use of too small fid syzbot reported a slab-out-of-bounds Read in isofs_fh_to_parent. Rated high severity (CVSS 7.1), this vulnerability is low attack complexity.
In the Linux kernel, the following vulnerability has been resolved: drm/xe: Fix an out-of-bounds shift when invalidating TLB When the size of the range invalidated is larger than. Rated high severity (CVSS 7.1), this vulnerability is low attack complexity. This Out-of-bounds Read vulnerability could allow attackers to read data from memory outside the intended buffer boundaries.
In the Linux kernel, the following vulnerability has been resolved: net: ppp: Add bound checking for skb data on ppp_sync_txmung Ensure we have enough data in linear buffer from skb before accessing. Rated high severity (CVSS 7.1), this vulnerability is low attack complexity. This Out-of-bounds Read vulnerability could allow attackers to read data from memory outside the intended buffer boundaries.
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid out-of-bounds access in f2fs_truncate_inode_blocks() syzbot reports an UBSAN issue as below: ------------[ cut. Rated high severity (CVSS 7.1), this vulnerability is low attack complexity. This Out-of-bounds Read vulnerability could allow attackers to read data from memory outside the intended buffer boundaries.
In the Linux kernel, the following vulnerability has been resolved: media: venus: hfi: add a check to handle OOB in sfr region sfr->buf_size is in shared memory and can be modified by malicious user. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. This Out-of-bounds Write vulnerability could allow attackers to write data beyond allocated buffer boundaries leading to code execution or crashes.
In the Linux kernel, the following vulnerability has been resolved: media: venus: hfi: add check to handle incorrect queue size qsize represents size of shared queued between driver and video. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity. This Out-of-bounds Write vulnerability could allow attackers to write data beyond allocated buffer boundaries leading to code execution or crashes.
In the Linux kernel, the following vulnerability has been resolved: media: venus: hfi_parser: add check to avoid out of bound access There is a possibility that init_codecs is invoked multiple times. Rated high severity (CVSS 7.1), this vulnerability is low attack complexity. This Out-of-bounds Read vulnerability could allow attackers to read data from memory outside the intended buffer boundaries.
In the Linux kernel, the following vulnerability has been resolved: media: venus: hfi_parser: refactor hfi packet parsing logic words_count denotes the number of words in total payload, while data. Rated high severity (CVSS 7.1), this vulnerability is low attack complexity. This Out-of-bounds Read vulnerability could allow attackers to read data from memory outside the intended buffer boundaries.
In the Linux kernel, the following vulnerability has been resolved: ext4: fix off-by-one error in do_split Syzkaller detected a use-after-free issue in ext4_insert_dentry that was caused by. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity.
A vulnerability classified as critical was found in PCMan FTP Server up to 2.0.7. Rated medium severity (CVSS 6.9), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability classified as critical has been found in PCMan FTP Server up to 2.0.7. Rated medium severity (CVSS 6.9), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability was found in PCMan FTP Server up to 2.0.7. Rated medium severity (CVSS 6.9), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability was found in PCMan FTP Server up to 2.0.7. Rated medium severity (CVSS 6.9), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability was found in PCMan FTP Server up to 2.0.7. Rated medium severity (CVSS 6.9), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Certain build processes for libuv and Node.js for 32-bit systems, such as for the nodejs binary package through nodejs_20.19.0+dfsg-2_i386.deb for Debian GNU/Linux, have an inconsistent off_t size. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
A vulnerability was found in Netgear EX6200 1.0.3.94. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability was found in Netgear EX6200 1.0.3.94. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability was found in Netgear EX6200 1.0.3.94 and classified as critical. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability has been found in Netgear EX6200 1.0.3.94 and classified as critical. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability, which was classified as critical, was found in Netgear EX6200 1.0.3.94. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability, which was classified as critical, has been found in Netgear EX6200 1.0.3.94. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability has been found in Netgear EX6200 1.0.3.94 and classified as critical. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability, which was classified as critical, was found in Netgear EX6200 1.0.3.94. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability, which was classified as critical, has been found in Netgear EX6120 1.0.3.94. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability classified as critical was found in Netgear EX6120 1.0.0.68. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A buffer overflow was addressed with improved input validation. Rated medium severity (CVSS 6.5), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
The issue was addressed with improved memory handling. Rated medium severity (CVSS 6.5), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
Tesla Model S oFono AT Command Heap-based Buffer Overflow Code Execution Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity. No vendor patch available.
A vulnerability was found in Netgear JWNR2000v2 1.0.0.11. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A vulnerability, which was classified as critical, was found in Netgear JWNR2000v2 1.0.0.11. Rated medium severity (CVSS 5.1), this vulnerability is low attack complexity. No vendor patch available.
A vulnerability, which was classified as critical, has been found in Netgear JWNR2000v2 1.0.0.11. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A vulnerability classified as critical was found in Netgear JWNR2000v2 1.0.0.11. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A vulnerability classified as critical has been found in Netgear JWNR2000v2 1.0.0.11. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Delta Electronics ISPSoft version 3.20 is vulnerable to an Out-Of-Bounds Write vulnerability that could allow an attacker to execute arbitrary code when parsing ISP file. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
Delta Electronics ISPSoft version 3.20 is vulnerable to an Out-Of-Bounds Write vulnerability that could allow an attacker to execute arbitrary code when parsing ISP file. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
Delta Electronics ISPSoft version 3.20 is vulnerable to a Stack-Based buffer overflow vulnerability that could allow an attacker to execute arbitrary code when parsing DVP file. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
Delta Electronics ISPSoft version 3.20 is vulnerable to an Out-Of-Bounds Write vulnerability that could allow an attacker to execute arbitrary code when parsing DVP file. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
Delta Electronics ISPSoft version 3.20 is vulnerable to a Stack-Based buffer overflow vulnerability that could allow an attacker to leverage debugging logic to execute arbitrary code when parsing. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
A vulnerability, which was classified as critical, was found in PCMan FTP Server up to 2.0.7. Rated medium severity (CVSS 6.9), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability classified as critical was found in code-projects School Billing System 1.0. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability, which was classified as critical, has been found in code-projects Product Management System 1.0. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability classified as critical was found in code-projects Simple Movie Ticket Booking System 1.0. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
Memory safety bug present in Firefox ESR 128.9, and Thunderbird 128.9. Rated high severity (CVSS 8.1), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
Memory safety bugs present in Firefox 137 and Thunderbird 137. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Memory safety bugs present in Firefox 137, Thunderbird 137, Firefox ESR 128.9, and Thunderbird 128.9. Rated high severity (CVSS 8.1), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
A vulnerability was identified in Thunderbird where XPath parsing could trigger undefined behavior due to missing null checks during attribute access. Rated medium severity (CVSS 4.8), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
Modification of specific WebGL shader attributes could trigger an out-of-bounds read, which, when chained with other vulnerabilities, could be used to escalate privileges. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
A vulnerability was found in code-projects Student Information Management System 1.0 and classified as critical. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability has been found in code-projects Theater Seat Booking System 1.0 and classified as critical. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability, which was classified as critical, was found in code-projects Clothing Store Management System up to 1.0. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability classified as critical was found in code-projects Prison Management System 1.0. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
In the Linux kernel, the following vulnerability has been resolved: vmxnet3: Fix packet corruption in vmxnet3_xdp_xmit_frame Andrew and Nikolay reported connectivity issues with Cilium's service. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. This Out-of-bounds Write vulnerability could allow attackers to write data beyond allocated buffer boundaries leading to code execution or crashes.
An integer overflow was addressed with improved input validation. Rated medium severity (CVSS 6.5), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
A vulnerability was found in code-projects Train Ticket Reservation System 1.0. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability was found in code-projects Personal Diary Management System 1.0 and classified as critical. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability classified as critical was found in Tenda W12 and i24 3.0.0.4(2887)/3.0.0.5(3644). Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability was found in TOTOLINK N150RT 3.4.0-B20190525 and classified as critical. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability has been found in TOTOLINK N150RT 3.4.0-B20190525 and classified as critical. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability, which was classified as critical, was found in TOTOLINK N150RT 3.4.0-B20190525. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability, which was classified as critical, has been found in TOTOLINK N150RT 3.4.0-B20190525. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability classified as critical was found in TOTOLINK N150RT 3.4.0-B20190525. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability classified as critical has been found in TOTOLINK N150RT 3.4.0-B20190525. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
quickjs-ng through 0.9.0 has an incorrect size calculation in JS_ReadBigInt for a BigInt, leading to a heap-based buffer overflow. Rated medium severity (CVSS 5.6), this vulnerability is no authentication required. Public exploit code available.
quickjs-ng through 0.9.0 has a missing length check in JS_ReadString for a string, leading to a heap-based buffer overflow. Rated medium severity (CVSS 5.6), this vulnerability is no authentication required. Public exploit code available.
A vulnerability classified as critical has been found in GL.iNet GL-A1300 Slate Plus, GL-AR300M16 Shadow, GL-AR300M Shadow, GL-AR750 Creta, GL-AR750S-EXT Slate, GL-AX1800 Flint, GL-AXT1800 Slate AX,. Rated high severity (CVSS 8.6), this vulnerability is low attack complexity. No vendor patch available.
z2d is a pure Zig 2D graphics library. Rated high severity (CVSS 7.3). No vendor patch available.
An unauthenticated attacker on the WAN interface, with the ability to intercept Dynamic DNS (DDNS) traffic between DDNS services and the modem, could manipulate specific responses to include code. Rated high severity (CVSS 7.7), this vulnerability is no authentication required. No vendor patch available.
The device exposes a web interface on ports TCP/3030 and TCP/9882. Rated high severity (CVSS 7.7), this vulnerability is no authentication required. No vendor patch available.
OpenPLC 3 through 64f9c11 has server.cpp Memory Corruption because a thread may access handleConnections arguments after the parent stack frame becomes unavailable. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
Under certain circumstances the iSTAR Configuration Utility (ICU) tool could have a buffer overflow issue. Rated critical severity (CVSS 9.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In xfig diagramming tool, a stack-overflow while running fig2dev allows memory corruption via local input manipulation via read_objects function. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A flaw was found in xfig. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
GIMP FLI File Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
TOTOLINK A830R V4.1.2cu.5182_B20201102, A950RG V4.1.2cu.5161_B20200903, A3000RU V5.9c.5185_B20201128, and A3100R V4.1.2cu.5247_B20211129 were found to contain a buffer overflow vulnerability in. Rated high severity (CVSS 7.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
TOTOLINK A830R V4.1.2cu.5182_B20201102, A950RG V4.1.2cu.5161_B20200903, A3000RU V5.9c.5185_B20201128, and A3100R V4.1.2cu.5247_B20211129 were found to contain a buffer overflow vulnerability in. Rated high severity (CVSS 7.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
TOTOLINK A810R V4.1.2cu.5182_B20201026 was found to contain a buffer overflow vulnerability in downloadFile.cgi through the v25 parameter. Rated high severity (CVSS 7.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
TOTOLINK A810R V4.1.2cu.5182_B20201026 was found to contain a buffer overflow vulnerability in the downloadFile.cgi through the v14 and v3 parameters. Rated high severity (CVSS 7.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
TOTOLINK A800R V4.1.2cu.5137_B20200730 was found to contain a buffer overflow vulnerability in downloadFile.cgi through the v25 parameter. Rated high severity (CVSS 7.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
TOTOLINK A800R V4.1.2cu.5137_B20200730 was found to contain a buffer overflow vulnerability in the downloadFile.cgi component. Rated high severity (CVSS 7.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
TOTOLINK A800R V4.1.2cu.5137_B20200730 was found to contain a buffer overflow vulnerability in downloadFile.cgi through the v14 parameter. Rated high severity (CVSS 7.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Sonos Era 300 Out-of-Bounds Write Remote Code Execution Vulnerability. Rated high severity (CVSS 8.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
Sonos Era 300 Heap-based Buffer Overflow Remote Code Execution Vulnerability. Rated high severity (CVSS 8.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
Luxion KeyShot Viewer KSP File Parsing Heap-based Buffer Overflow Remote Code Execution Vulnerability. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In the Tenda ac9 v1.0 router with firmware V15.03.05.14_multi, there is a stack overflow vulnerability in /goform/WifiWpsStart, which may lead to remote arbitrary code execution. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
In Tenda ac9 v1.0 with firmware V15.03.05.14_multi, the rebootTime parameter of /goform/SetSysAutoRebbotCfg has a stack overflow vulnerability, which can lead to remote arbitrary code execution. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
In Tenda AC9 v1.0 with firmware V15.03.05.14_multi, the security parameter of /goform/WifiBasicSet has a stack overflow vulnerability, which can lead to remote arbitrary code execution. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.