CVE-2025-71126: Linux kernel · mptcp: avoid deadlock on fallback while reinjecting
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.5 High · fixed in ffb8c27b0539dd90262d1021488e7817fae57c42 : patch Linux kernel soon.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 18% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers can reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in ffb8c27b0539dd90262d1021488e7817fae57c42, 252892d5a6a2f163ce18f32716e46fa4da7d4e79, 0107442e82c0f8d6010e07e6030741c59c520d6e +6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 14 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in– |
AI-suggested
A fix is available and has been applied in Linux kernel versions 6.1.160, 6.6.120, 6.12.64, and 6.16. Users and administrators should upgrade to these or later kernel versions to remediate the issue. No additional mitigation actions are required beyond applying the official patches.
Description
CVE-2025-71126 is a high-severity vulnerability in the Linux kernel's Multipath TCP (MPTCP) implementation that can cause a deadlock during fallback reinjection. The issue arises when the packet scheduler attempts reinjection after receiving an MP_FAIL before the infinite map is transmitted, leading to recursive locking and a deadlock. This flaw affects multiple Linux kernel versions prior to 6.1.160, 6.6.120, 6.12.64, and 6.16, and has been fixed in these versions.
References
- git.kernel.org/stable/c/0107442e82c0f8d6010e07e6030741c59c520d6e (opens in a new tab)
- git.kernel.org/stable/c/252892d5a6a2f163ce18f32716e46fa4da7d4e79 (opens in a new tab)
- git.kernel.org/stable/c/0ca9fb4335e726dab4f23b3bfe87271d8f005f41 (opens in a new tab)
- git.kernel.org/stable/c/50f47c02be419bf0a3ae94c118addf67beef359f (opens in a new tab)
- git.kernel.org/stable/c/ffb8c27b0539dd90262d1021488e7817fae57c42 (opens in a new tab)