CVE-2026-31402: Linux kernel · Out-of-bounds Write
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical · fixed in f9fcb4441f6c02bb20c2eb340101e27dfe23607c : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 1.1% chance of exploitation in 30 days – higher than 67% 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
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in f9fcb4441f6c02bb20c2eb340101e27dfe23607c, dad0c3c0a8e5d1d6eb0fc455694ce3e25e6c57d0, c9452c0797c95cf2378170df96cf4f4b3bca7eff +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 3 Apr 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
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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AI-suggested
A fix for this vulnerability is available and has been applied in multiple Linux kernel commits. The fix adds bounds checking to prevent copying oversized LOCK denied responses into the replay cache buffer. Users should update their Linux kernel to a fixed version containing these commits. No other mitigations or workarounds are noted in the vendor advisory.
Description
A heap overflow vulnerability exists in the Linux kernel's NFSv4.0 server (nfsd) due to an undersized replay cache buffer that does not account for large lock owner strings in LOCK denied responses. This flaw can be triggered remotely by an unauthenticated attacker using two cooperating NFSv4.0 clients, leading to a slab-out-of-bounds write that corrupts adjacent heap memory. The issue has been fixed by adding a length check before copying responses into the replay buffer, skipping caching if the response is too large while still caching the status. The vulnerability has a critical severity with a CVSS score of 9.8 and affects Linux kernel version 2.6.12. No known exploits in the wild have been reported.
References
- git.kernel.org/stable/c/f9fcb4441f6c02bb20c2eb340101e27dfe23607c (opens in a new tab)
- git.kernel.org/stable/c/2665887a69437a8a4f552f69509eecfb73d4aa19 (opens in a new tab)
- git.kernel.org/stable/c/c9452c0797c95cf2378170df96cf4f4b3bca7eff (opens in a new tab)
- git.kernel.org/stable/c/8afb437ea1f70cacb4bbdf11771fb5c4d720b965 (opens in a new tab)
- git.kernel.org/stable/c/dad0c3c0a8e5d1d6eb0fc455694ce3e25e6c57d0 (opens in a new tab)
- git.kernel.org/stable/c/0f0e2a54a31a7f9ad2915db99156114872317388 (opens in a new tab)
- git.kernel.org/stable/c/ae8498337dfdfda71bdd0b807c9a23a126011d76 (opens in a new tab)
- git.kernel.org/stable/c/5133b61aaf437e5f25b1b396b14242a6bb0508e2 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-31402 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2454844 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31402.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:14823 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:14925 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:14869 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:15883 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:13566 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:19569 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:13936 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:13734 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:10108 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:11313 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:13565 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:19568 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:13577 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36530 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:14165 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:13664 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:13681 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36531 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36532 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36533 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36534 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:13578 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:14137 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:14301 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)