Skip to main content

Linux Kernel CVE-2025-38491

MEDIUM
Improper Locking (CWE-667)
2025-07-28 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Information Disclosure Ubuntu Debian Linux Debian Linux Red Hat Suse
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

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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

DescriptionCVE.org

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-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-2026-24061 CRITICAL POC
9.8 Jan 21

GNU Inetutils telnetd through version 2.7 contains a critical authentication bypass that allows remote attackers to gain
CVE-2025-32433 CRITICAL POC
10.0 Apr 16

Erlang/OTP SSH server allows unauthenticated remote code execution by exploiting a flaw in SSH protocol message handling
CVE-2017-11610 HIGH POC
8.8 Aug 23

The XML-RPC server in supervisor before 3.0.1, 3.1.x before 3.1.4, 3.2.x before 3.2.4, and 3.3.x before 3.3.3 allows rem
CVE-2015-0235 CRITICAL POC
10.0 Jan 28

Heap-based buffer overflow in the __nss_hostname_digits_dots function in glibc 2.2, and other 2.x versions before 2.18,

CVE-2014-3704 HIGH POC
7.5 Oct 16

The expandArguments function in the database abstraction API in Drupal core 7.x before 7.32 does not properly construct

CVE-2013-0156 HIGH POC
7.5 Jan 13

active_support/core_ext/hash/conversions.rb in Ruby on Rails before 2.3.15, 3.0.x before 3.0.19, 3.1.x before 3.1.10, an
CVE-2017-12629 CRITICAL POC
9.8 Oct 14

Remote code execution occurs in Apache Solr before 7.1 with Apache Lucene before 7.1 by exploiting XXE in conjunction wi
CVE-2017-14492 CRITICAL POC
9.8 Oct 03

Heap-based buffer overflow in dnsmasq before 2.78 allows remote attackers to cause a denial of service (crash) or execut
CVE-2014-2323 CRITICAL POC
9.8 Mar 14

SQL injection vulnerability in mod_mysql_vhost.c in lighttpd before 1.4.35 allows remote attackers to execute arbitrary

CVE-2016-2098 HIGH POC
7.3 Apr 07

Action Pack in Ruby on Rails before 3.2.22.2, 4.x before 4.1.14.2, and 4.2.x before 4.2.5.2 allows remote attackers to e
CVE-2016-6662 CRITICAL POC
9.8 Sep 20

Oracle MySQL through 5.5.52, 5.6.x through 5.6.33, and 5.7.x through 5.7.15; MariaDB before 5.5.51, 10.0.x before 10.0.2

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-2020-12658 CRITICAL
9.8

Same technique Information Disclosure

View all
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
CVE-2023-7028 CRITICAL POC
10.0
CVE-2017-0213 HIGH POC
7.3

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