Skip to main content

Linux Kernel CVE-2025-38491

MEDIUM
Improper Locking (CWE-667)
2025-07-28 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Information Disclosure Linux Debian Ubuntu Debian Linux
5.5
CVSS 3.1 · NVD
Share

Severity by source

NVD PRIMARY
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
SUSE
MEDIUM
qualitative
Red Hat
5.5 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Analysis Generated
May 12, 2026 - 13:33 vuln.today
CVE Published
Jul 28, 2025 - 12:15 nvd
MEDIUM 5.5

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

mptcp: make fallback action and fallback decision atomic

Syzkaller reported the following splat:

WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 __mptcp_do_fallback net/mptcp/protocol.h:1223 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_do_fallback net/mptcp/protocol.h:1244 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 check_fully_established net/mptcp/options.c:982 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153 Modules linked in: CPU: 1 UID: 0 PID: 7704 Comm: syz.3.1419 Not tainted 6.16.0-rc3-gbd5ce2324dba #20 PREEMPT(voluntary) Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:__mptcp_do_fallback net/mptcp/protocol.h:1223 [inline] RIP: 0010:mptcp_do_fallback net/mptcp/protocol.h:1244 [inline] RIP: 0010:check_fully_established net/mptcp/options.c:982 [inline] RIP: 0010:mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153 Code: 24 18 e8 bb 2a 00 fd e9 1b df ff ff e8 b1 21 0f 00 e8 ec 5f c4 fc 44 0f b7 ac 24 b0 00 00 00 e9 54 f1 ff ff e8 d9 5f c4 fc 90 <0f> 0b 90 e9 b8 f4 ff ff e8 8b 2a 00 fd e9 8d e6 ff ff e8 81 2a 00 RSP: 0018:ffff8880a3f08448 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8880180a8000 RCX: ffffffff84afcf45 RDX: ffff888090223700 RSI: ffffffff84afdaa7 RDI: 0000000000000001 RBP: ffff888017955780 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8880180a8910 R14: ffff8880a3e9d058 R15: 0000000000000000 FS: 00005555791b8500(0000) GS:ffff88811c495000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2800b7 CR3: 0000000058e44000 CR4: 0000000000350ef0 Call Trace: <IRQ> tcp_reset+0x26f/0x2b0 net/ipv4/tcp_input.c:4432 tcp_validate_incoming+0x1057/0x1b60 net/ipv4/tcp_input.c:5975 tcp_rcv_established+0x5b5/0x21f0 net/ipv4/tcp_input.c:6166 tcp_v4_do_rcv+0x5dc/0xa70 net/ipv4/tcp_ipv4.c:1925 tcp_v4_rcv+0x3473/0x44a0 net/ipv4/tcp_ipv4.c:2363 ip_protocol_deliver_rcu+0xba/0x480 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x2f1/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ip_local_deliver+0x1be/0x560 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:469 [inline] ip_rcv_finish net/ipv4/ip_input.c:447 [inline] NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ip_rcv+0x514/0x810 net/ipv4/ip_input.c:567 __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5975 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6088 process_backlog+0x301/0x1360 net/core/dev.c:6440 __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7453 napi_poll net/core/dev.c:7517 [inline] net_rx_action+0xb44/0x1010 net/core/dev.c:7644 handle_softirqs+0x1d0/0x770 kernel/softirq.c:579 do_softirq+0x3f/0x90 kernel/softirq.c:480 </IRQ> <TASK> __local_bh_enable_ip+0xed/0x110 kernel/softirq.c:407 local_bh_enable include/linux/bottom_half.h:33 [inline] inet_csk_listen_stop+0x2c5/0x1070 net/ipv4/inet_connection_sock.c:1524 mptcp_check_listen_stop.part.0+0x1cc/0x220 net/mptcp/protocol.c:2985 mptcp_check_listen_stop net/mptcp/mib.h:118 [inline] __mptcp_close+0x9b9/0xbd0 net/mptcp/protocol.c:3000 mptcp_close+0x2f/0x140 net/mptcp/protocol.c:3066 inet_release+0xed/0x200 net/ipv4/af_inet.c:435 inet6_release+0x4f/0x70 net/ipv6/af_inet6.c:487 __sock_release+0xb3/0x270 net/socket.c:649 sock_close+0x1c/0x30 net/socket.c:1439 __fput+0x402/0xb70 fs/file_table.c:465 task_work_run+0x150/0x240 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xd4 ---truncated---

AnalysisAI

A race condition in the Linux kernel's MPTCP (Multipath TCP) protocol implementation allows local attackers with limited privileges to trigger a kernel warning and denial of service by causing non-atomic fallback decisions and actions during connection establishment. The vulnerability (CWE-667: Improper Locking) arises from unsynchronized access to fallback state in mptcp_do_fallback() when processing incoming TCP options, enabling a local user to crash the system or hang connections via crafted MPTCP packets. EPSS score of 0.03% indicates low real-world exploitation probability despite moderate CVSS impact severity.

Technical ContextAI

The MPTCP protocol subsystem in the Linux kernel implements multipath transmission over TCP. The vulnerability exists in the fallback mechanism (net/mptcp/protocol.h and net/mptcp/options.c), which is invoked during the connection establishment phase when the kernel determines whether to switch from MPTCP to standard TCP. The bug is a data race (CWE-667: Improper Locking) where the fallback decision and the action taken to enforce it are not performed atomically under lock, allowing concurrent modification of fallback state from different code paths (specifically during TCP reset handling in tcp_reset() and incoming option processing in mptcp_incoming_options()). This creates a window where multiple CPUs or interrupt contexts can observe inconsistent fallback state, triggering kernel assertions in __mptcp_do_fallback().

RemediationAI

Vendor-released patch available: Apply the MPTCP fallback atomicity fix from Linux kernel stable branches. The fix is available in these commits: 1d82a8fe6ee4afdc92f4e8808c9dad2a6095bbc5, 54999dea879fecb761225e28f274b40662918c30, 5586518bec27666c747cd52aabb62d485686d0bf, 75a4c9ab8a7af0d76b31ccd1188ed178c38b35d2, and f8a1d9b18c5efc76784f5a326e905f641f839894 (referenced via https://git.kernel.org/stable/c/[commit-hash]). For Debian systems, updates are available via debian-lts-announce mailing list (https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html). Siemens products may be affected; check Siemens PSA-032379 (https://cert-portal.siemens.com/productcert/html/ssa-032379.html). Workaround: Disable MPTCP on systems where it is not required by disabling the CONFIG_MPTCP kernel option during compilation or by administratively blocking MPTCP traffic if the kernel is already built with support. This mitigates the attack surface but disables MPTCP functionality for legitimate users.

More in Debian Linux

View all
CVE-2021-44228 CRITICAL POC
10.0 Dec 10

Apache Log4j2 contains a critical JNDI injection vulnerability known as 'Log4Shell' that allows unauthenticated remote c
CVE-2019-11043 CRITICAL POC
9.8 Oct 28

In PHP versions 7.1.x below 7.1.33, 7.2.x below 7.2.24 and 7.3.x below 7.3.11 in certain configurations of FPM setup it

CVE-2012-1823 CRITICAL POC
9.8 May 11

sapi/cgi/cgi_main.c in PHP before 5.3.12 and 5.4.x before 5.4.2, when configured as a CGI script (aka php-cgi), does not
CVE-2014-6271 CRITICAL POC
9.8 Sep 24

GNU Bash through 4.3 processes trailing strings after function definitions in the values of environment variables, which
CVE-2017-7494 CRITICAL POC
9.8 May 30

Samba since version 3.5.0 and before 4.6.4, 4.5.10 and 4.4.14 is vulnerable to remote code execution vulnerability, allo
CVE-2012-0507 CRITICAL POC
9.8 Jun 07

Unspecified vulnerability in the Java Runtime Environment (JRE) component in Oracle Java SE 7 Update 2 and earlier, 6 Up
CVE-2025-49113 CRITICAL POC
9.9 Jun 02

Roundcube Webmail contains a critical PHP object deserialization vulnerability (CVE-2025-49113, CVSS 9.9) that allows au
CVE-2022-30333 HIGH POC
7.5 May 09

RARLAB UnRAR before 6.12 on Linux and UNIX allows directory traversal to write to files during an extract (aka unpack) o
CVE-2016-3714 HIGH POC
8.4 May 05

The (1) EPHEMERAL, (2) HTTPS, (3) MVG, (4) MSL, (5) TEXT, (6) SHOW, (7) WIN, and (8) PLT coders in ImageMagick before 6.
CVE-2017-12617 HIGH POC
8.1 Oct 04

When running Apache Tomcat versions 9.0.0.M1 to 9.0.0, 8.5.0 to 8.5.22, 8.0.0.RC1 to 8.0.46 and 7.0.0 to 7.0.81 with HTT
CVE-2020-1938 CRITICAL POC
9.8 Feb 24

When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to Apache Tomcat. Rate
CVE-2018-7602 CRITICAL POC
9.8 Jul 19

A remote code execution vulnerability exists within multiple subsystems of Drupal 7.x and 8.x. Rated critical severity (

Same weakness CWE-667 – Improper Locking

View all
CVE-2025-43510 HIGH POC
7.8
CVE-2019-5886 CRITICAL POC
9.8
CVE-2020-13246 HIGH POC
7.5
CVE-2019-15513 HIGH POC
7.5
CVE-2019-11599 HIGH POC
7.0
CVE-2023-21400 MEDIUM POC
6.7
CVE-2021-20291 MEDIUM POC
6.5
CVE-2026-53049 CRITICAL
9.8

Same technique Information Disclosure

View all
CVE-2019-2725 CRITICAL POC
9.8
CVE-2021-34523 CRITICAL POC
9.0
CVE-2013-2251 CRITICAL POC
9.8
CVE-2017-5638 CRITICAL POC
9.8
CVE-2025-24813 CRITICAL POC
9.8
CVE-2015-1701 HIGH POC
7.8
CVE-2017-0147 HIGH POC
7.5
CVE-2014-6324 HIGH POC
8.8

Vendor StatusVendor

SUSE

Severity: Medium
Product Status
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.50 Container suse/sl-micro/6.1/base-os-container:2.2.1-5.29 Image SL-Micro Image SL-Micro-Azure Image SL-Micro-BYOS-Azure Image SL-Micro-BYOS-EC2 Image SL-Micro-BYOS-GCE Image SL-Micro-EC2 Image SLE-Micro Image SLE-Micro-Azure Image SLE-Micro-BYOS Image SLE-Micro-BYOS-Azure Image SLE-Micro-BYOS-EC2 Image SLE-Micro-BYOS-GCE Image SLE-Micro-EC2 Image SLE-Micro-GCE Image SUSE-Multi-Linux-Manager-Proxy-BYOS-Azure Image SUSE-Multi-Linux-Manager-Proxy-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-Azure-llc Image SUSE-Multi-Linux-Manager-Server-Azure-ltd Image SUSE-Multi-Linux-Manager-Server-BYOS-Azure Image SUSE-Multi-Linux-Manager-Server-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Server-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-EC2-llc Image SUSE-Multi-Linux-Manager-Server-EC2-ltd Affected
Container suse/sl-micro/6.0/kvm-os-container:2.1.3-6.73 Container suse/sl-micro/6.1/kvm-os-container:2.2.1-5.32 Affected
Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.85 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.24 Affected
Image SLES-Azure-3P Image SLES-Azure-Basic Image SLES-Azure-Standard Image SLES-BYOS-Azure Image SLES-BYOS-EC2 Image SLES-BYOS-GCE Image SLES-CHOST-BYOS-Aliyun Image SLES-CHOST-BYOS-Azure Image SLES-CHOST-BYOS-EC2 Image SLES-CHOST-BYOS-GCE Image SLES-CHOST-BYOS-GDC Image SLES-CHOST-BYOS-SAP-CCloud Image SLES-EC2 Image SLES-GCE Image SLES-GCE-3P Image SLES-Hardened-BYOS-Azure Image SLES-Hardened-BYOS-EC2 Image SLES-Hardened-BYOS-GCE Image SLES-SAPCAL-Azure Image SLES-SAPCAL-EC2 Image SLES-SAPCAL-GCE Affected
Image SLES-SAP-Azure Image SLES-SAP-Azure-3P Image SLES-SAP-BYOS-Azure Image SLES-SAP-BYOS-EC2 Image SLES-SAP-BYOS-GCE Image SLES-SAP-EC2 Image SLES-SAP-GCE Image SLES-SAP-GCE-3P Affected

Share

CVE-2025-38491 vulnerability details – vuln.today
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy