CVE-2026-31700: Linux kernel · Race Condition
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 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
- 0.1% chance of exploitation in 30 days – higher than 1% 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 +69
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 May 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-ibmpkg:deb/ubuntu/linux-ibm?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 and should be applied to affected Linux kernel versions. The fix copies the vnet_hdr data to a stack-local variable before validation and use, eliminating the race condition. Users should update to patched kernel versions as listed in the affectedVersions field. No additional mitigation is indicated by the vendor advisory.
Description
A time-of-check to time-of-use (TOCTOU) race condition vulnerability was fixed in the Linux kernel's packet socket code (tpacket_snd) when PACKET_VNET_HDR is enabled. The issue allowed a concurrent userspace thread to modify the vnet_hdr fields between validation and use, potentially bypassing safety checks. The fix involves copying the vnet_hdr from the mmap'd ring buffer to a stack-local variable before validation and use, aligning with other kernel consumers' approach.
References
- ubuntu.com/security/CVE-2026-31700 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-31700 (opens in a new tab)
- git.kernel.org/linus/2c054e17d9d41f1020376806c7f750834ced4dc5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8488-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8488-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8507-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8569-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8567-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8596-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8603-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8606-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8607-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8608-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8609-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-3 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-31700 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- git.kernel.org/stable/c/0f4c9754956b86de158a4af5278c5cf5bda9439e (opens in a new tab)
- git.kernel.org/stable/c/1490f82353bdabc09265a74e645b07f05cf4188e (opens in a new tab)
- git.kernel.org/stable/c/28324a3b62d9ce7f9bdd65a8ce63f382041d1b27 (opens in a new tab)
- git.kernel.org/stable/c/2c054e17d9d41f1020376806c7f750834ced4dc5 (opens in a new tab)
- git.kernel.org/stable/c/3a1bf9116ea31470b89692585c3910dfe830dcdd (opens in a new tab)
- git.kernel.org/stable/c/48a6ef291a17639e1b6ae0fbe9c8b2bb87d7804b (opens in a new tab)
- git.kernel.org/stable/c/714aa973da8163925eda7efd49361ccbee21ee46 (opens in a new tab)
- git.kernel.org/stable/c/74e2db36fe50e3ad9d5300d7fd0e6e2a15a6d121 (opens in a new tab)