CVE-2026-74692: Linux kernel · net/smc: fix TOCTOU race between smc_listen_out() and listener close
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, 14:05 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
A patch is available that fixes the TOCTOU race by changing the locking order in the SMC socket code. Users should apply the official Linux kernel updates that include this fix. After updating, a system reboot is required to apply the changes. No additional mitigation is necessary once patched.
Description
A time-of-check to time-of-use (TOCTOU) race condition was fixed in the Linux kernel's SMC socket implementation. The vulnerability involves a race between smc_listen_out() and listener close operations, which can cause a memory leak by enqueuing child sockets on a closed listener. This can lead to kernel memory exhaustion when a remote peer repeatedly opens TCP connections while the server closes sockets. The issue has been addressed by moving the lock acquisition to cover the state check and enqueue operation atomically.
References
- nvd.nist.gov/vuln/detail/CVE-2026-74692 (opens in a new tab)
- git.kernel.org/stable/c/00f89433777236ced4771211047fb5d4cd581cea (opens in a new tab)
- git.kernel.org/stable/c/01865e1ddb126b25ac9eba5cdd7ec49e11183a64 (opens in a new tab)
- git.kernel.org/stable/c/185a4caeecabc150106deda1da170b09f2ad803f (opens in a new tab)
- git.kernel.org/stable/c/53c7938d8bcfde3296ec1a347ba2a9393c1fdcfa (opens in a new tab)
- git.kernel.org/stable/c/78e5ebcd1c10ed7c8bda0a99e0abd5b62da86d67 (opens in a new tab)
- git.kernel.org/stable/c/feb71634bb1abab3e8fb5cde874b27001cc1282e (opens in a new tab)
- git.kernel.org/stable/c/ff5bcd804b5bc5c64736b7d318c20e12ea9506b8 (opens in a new tab)
- ubuntu.com/security/CVE-2026-74692 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-74692 (opens in a new tab)
- msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-74692.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)