CVE-2026-31707: Linux kernel · ksmbd: validate response sizes in ipc_validate_msg()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.1 High · fixed in d6a6aa81eac2c9bff66dc6e191179cb69a14426b : patch Linux kernel soon.
Data as of 30 Oct 2026, 12:49 UTC
Thin evidence
One scorer or none| CNA (Linux) | CVSS 3.1 | 7.1 |
|---|
- Patch
- Available – fixed in d6a6aa81eac2c9bff66dc6e191179cb69a14426b, bf396208418371174869baba9434535cd3288e80, 52518503a1a00bc33e9522c4eb05df023e3ae978 +3
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | 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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| LinuxLinux | Affected
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AI-suggested
A patch is available and has been applied in fixed Linux kernel commits referenced by their hashes. Users should update to a fixed kernel version that includes these commits. Since this is a kernel vulnerability, updating the kernel to a patched version is the recommended mitigation. The vendor manages remediation for this cloud-hosted service if applicable. No additional mitigations are specified.
Description
CVE-2026-31707 is a high-severity vulnerability in the Linux kernel's ksmbd component affecting version 5.15. It involves integer overflow in the ipc_validate_msg() function when calculating expected message sizes for certain response types, allowing unverified length values to be trusted downstream. The flaw arises from arithmetic on attacker-controlled fields that can wrap around, bypassing size checks and potentially leading to memory corruption. The issue has been fixed by adding overflow checks and bounds validation to prevent these overflows.
References
- git.kernel.org/stable/c/52518503a1a00bc33e9522c4eb05df023e3ae978 (opens in a new tab)
- git.kernel.org/stable/c/bf396208418371174869baba9434535cd3288e80 (opens in a new tab)
- git.kernel.org/stable/c/7dd0c858e1909769a4c91842724315ee74f1a5f1 (opens in a new tab)
- git.kernel.org/stable/c/299db777ea0cfa5c407e41b045c24a14c034c27b (opens in a new tab)
- git.kernel.org/stable/c/99c631d0366c1eab8fb188fe66425f4581ebdde4 (opens in a new tab)
- git.kernel.org/stable/c/d6a6aa81eac2c9bff66dc6e191179cb69a14426b (opens in a new tab)