CVE-2026-31447: Linux kernel · Improper Input Validation
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.8 High · fixed in d787d3ae96648dc14a3b7ca8fde817177e82c1c7 : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% 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 cannot 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 d787d3ae96648dc14a3b7ca8fde817177e82c1c7, b77de3fceafbb39f30e4ff5dc986f863d5456417, ad1f6d608f33f59d21a3d025615d6786a6443998 +5
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 22 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 is available and has been applied in the Linux kernel as indicated by the fixed commit hashes. Users and administrators should update their Linux kernel to a version including these fixes to mitigate this vulnerability. No additional mitigation steps are indicated by the vendor advisory.
Description
CVE-2026-31447 is a high-severity vulnerability in the Linux kernel's ext4 filesystem implementation. It concerns the handling of bigalloc feature when the s_first_data_block field is not zero. Mounting ext4 filesystems with bigalloc enabled and s_first_data_block set to a non-zero value is unsupported and was not properly rejected, leading to potential security issues. This flaw has been fixed in specific Linux kernel commits.
References
- git.kernel.org/stable/c/5ad6d994255e27a3254079dfb50ca861fc31f2d0 (opens in a new tab)
- git.kernel.org/stable/c/3a926957cc95899ef88529710836edadc03c71a1 (opens in a new tab)
- git.kernel.org/stable/c/7b58c110b4e1f028eb38eec9ed3555e9be81c8b0 (opens in a new tab)
- git.kernel.org/stable/c/b77de3fceafbb39f30e4ff5dc986f863d5456417 (opens in a new tab)
- git.kernel.org/stable/c/d787d3ae96648dc14a3b7ca8fde817177e82c1c7 (opens in a new tab)
- git.kernel.org/stable/c/ad1f6d608f33f59d21a3d025615d6786a6443998 (opens in a new tab)
- git.kernel.org/stable/c/7d5b04290156c3fc316eecc86a4f9d201ab7d44a (opens in a new tab)
- git.kernel.org/stable/c/3822743dc20386d9897e999dbb990befa3a5b3f8 (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)