CVE-2025-71088: Linux kernel · mptcp: fallback earlier on simult connection
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-1052.55~22.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1052.55~22.04.1, 6.8.0-1059.65~22.04.1, 6.8.0-1054.57~22.04.1 +42
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 13 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 |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-29.29?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1015.15?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1015.15?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1018.19?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1014.14?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available and has been backported to affected Linux kernel versions. Users should apply the official kernel updates provided by their distribution to remediate this issue. No additional mitigation steps are required beyond applying the vendor-supplied fixes.
Description
A race condition vulnerability in the Linux kernel's Multipath TCP (MPTCP) implementation was resolved. The issue involved a simult-connect race causing inconsistent fallback status in TCP subflows, leading to a kernel warning and potential crash when processing incoming data. The flaw was fixed by moving the fallback check to an earlier stage during syn-ack generation. This vulnerability affects specific Linux kernel versions and has a medium severity rating with an impact on availability.
References
- ubuntu.com/security/CVE-2025-71088 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-71088 (opens in a new tab)
- git.kernel.org/linus/71154bbe49423128c1c8577b6576de1ed6836830 (opens in a new tab)
- git.kernel.org/stable/c/25f1ae942c097b7ae4ce5c2b9c6fefb8e3672b86 (opens in a new tab)
- git.kernel.org/stable/c/71154bbe49423128c1c8577b6576de1ed6836830 (opens in a new tab)
- git.kernel.org/stable/c/79f80a7a47849ef1b3c25a0bedcc448b9cb551c1 (opens in a new tab)
- git.kernel.org/stable/c/b5f46a08269265e2f5e87d855287d6d22de0a32b (opens in a new tab)
- git.kernel.org/stable/c/c9bf315228287653522894df9d851e9b43db9516 (opens in a new tab)
- ubuntu.com/security/notices/USN-8179-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8184-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8179-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8185-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8179-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8203-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8204-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8185-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8179-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8258-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8260-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8261-1 (opens in a new tab)