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VulnerabilityPublished Updated

CVE-2026-31577: Linux kernel · nilfs2: fix NULL i_assoc_inode dereference in nilfs_mdt_save_to_shadow_map

Affects Linux kernelSource GCVE Database

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Not known to be exploited.

Data as of 12 Nov 2026, 03:33 UTC

Severity
Medium

Rated Medium by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: 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 11 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Linux LinuxAffected
  • 4.14.296 – 5.17.10
6 affected builds
Fixed in–

AI-suggested

A fix is available that initializes the btree node cache at mount time, preventing the NULL dereference. Users should upgrade to versions where this fix is applied. The affected versions listed are =4.14.296, =4.19.245, =5.4.196, =5.10.118, =5.15.42, and =5.17.10. No further mitigation steps are indicated.

Description

A NULL pointer dereference vulnerability exists in the Linux kernel's nilfs2 filesystem code. The issue occurs because the DAT inode's btree node cache (i_assoc_inode) is lazily initialized but assumed to be initialized during garbage collection operations. If the NILFS_IOCTL_CLEAN_SEGMENTS ioctl is called immediately after mounting before any btree operation, a NULL dereference leads to a general protection fault. The flaw is fixed by initializing the btree node cache at mount time.

References

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