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VulnerabilityPublished Updated

CVE-2026-31447: Linux kernel · Improper Input Validation

Affects Linux kernelSource CVE Database V5

0

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

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
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:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 22 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 281b59959707dfae03ce038cdf231bf4904e170c, < d787d3ae96648dc14a3b7ca8fde817177e82c1c7
Fixed in
  • d787d3ae96648dc14a3b7ca8fde817177e82c1c7
LinuxLinuxAffected
  • ≥ 281b59959707dfae03ce038cdf231bf4904e170c, < b77de3fceafbb39f30e4ff5dc986f863d5456417
Fixed in
  • b77de3fceafbb39f30e4ff5dc986f863d5456417
LinuxLinuxAffected
  • ≥ 281b59959707dfae03ce038cdf231bf4904e170c, < ad1f6d608f33f59d21a3d025615d6786a6443998
Fixed in
  • ad1f6d608f33f59d21a3d025615d6786a6443998
LinuxLinuxAffected
  • ≥ 281b59959707dfae03ce038cdf231bf4904e170c, < 3822743dc20386d9897e999dbb990befa3a5b3f8
Fixed in
  • 3822743dc20386d9897e999dbb990befa3a5b3f8
LinuxLinuxAffected
  • ≥ 281b59959707dfae03ce038cdf231bf4904e170c, < 7d5b04290156c3fc316eecc86a4f9d201ab7d44a
Fixed in
  • 7d5b04290156c3fc316eecc86a4f9d201ab7d44a
LinuxLinuxAffected
  • ≥ 281b59959707dfae03ce038cdf231bf4904e170c, < 7b58c110b4e1f028eb38eec9ed3555e9be81c8b0
Fixed in
  • 7b58c110b4e1f028eb38eec9ed3555e9be81c8b0

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

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