CVE-2026-74696: Linux kernel · tcp: fix TFO max_qlen accounting across reuseport migration
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.5 High · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 15:59 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +27
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 22 Aug 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 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther 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
An official fix is available and should be applied. The vulnerability has been resolved in updated Linux kernel versions. Users should update to the patched kernel versions listed in the affectedVersions field and reboot to apply the fix.
Description
A vulnerability in the Linux kernel's TCP_FASTOPEN implementation causes inaccurate accounting of the max_qlen parameter during SO_REUSEPORT listener migration. This leads to the listener allowing more pending Fast Open requests than configured, potentially causing a denial of service due to resource exhaustion. The issue arises because the accounting increments and decrements occur on different sockets after migration, causing the queue length to drift negative and the limit to be ineffective. This vulnerability affects specific Linux kernel versions and has been addressed by correcting the accounting during migration.
References
- nvd.nist.gov/vuln/detail/CVE-2026-74696 (opens in a new tab)
- git.kernel.org/stable/c/585fc5247d14939a561056aa2addd9b7c2b1f670 (opens in a new tab)
- git.kernel.org/stable/c/6e10ee56524a26b250229ad348637825646ddb88 (opens in a new tab)
- git.kernel.org/stable/c/a0ab2ba83e35159d81cec830a92e885ecf8139be (opens in a new tab)
- git.kernel.org/stable/c/a66e869cf0c90c1e47ae75f72b6482acbfc808ff (opens in a new tab)
- git.kernel.org/stable/c/b6247e0f96bd825ffb2005257f6177b5e642dee6 (opens in a new tab)
- git.kernel.org/stable/c/d974618b2097453778389d385e3741629c40e0a3 (opens in a new tab)
- git.kernel.org/stable/c/e98f0d80b9cccb5f828425d2004f9686e7d1ae24 (opens in a new tab)
- ubuntu.com/security/CVE-2026-74696 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-74696 (opens in a new tab)
- msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-74696.json (opens in a new tab)
- support.microsoft.com/lifecycle (opens in a new tab)
- first.org/cvss (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8886-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-2 (opens in a new tab)