PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-31457 Linux CVE debrief

A vulnerability was found in the Linux kernel, specifically in the DAMON (Data Access Monitoring) subsystem. The issue arises from a missing check for the 'nr' field in the 'contexts' structure, which can lead to a NULL pointer dereference when certain functions are called. This vulnerability can be exploited by setting 'nr_contexts' to 0 via sysfs while DAMON is running, causing the functions to dereference 'contexts_arr[0]' and resulting in a NULL pointer dereference.

Vendor
Linux
Product
Unknown
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-22
Original CVE updated
2026-06-05
Advisory published
2026-04-22
Advisory updated
2026-06-05

Who should care

Users of the Linux kernel, particularly those using versions 6.17, 6.19, and 7.0 RC versions, should be aware of this vulnerability. The vulnerability can be mitigated by applying the provided patches.

Technical summary

The vulnerability is caused by a missing check for 'contexts->nr' in the 'damon_sysfs_repeat_call_fn' function. This function calls other functions without checking if 'nr_contexts' is set to 0, which can lead to a NULL pointer dereference. The affected functions are 'damon_sysfs_upd_tuned_intervals', 'damon_sysfs_upd_schemes_stats', and 'damon_sysfs_upd_schemes_effective_quotas'.

Defensive priority

MEDIUM

Recommended defensive actions

  • Apply the provided patches to fix the vulnerability.
  • Monitor and update Linux kernel versions to ensure the latest security patches are applied.

Evidence notes

The vulnerability was resolved by adding a check for 'contexts->nr' in the affected functions. Patches are available for Linux kernel versions 6.17, 6.19, and 7.0 RC versions.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-31457 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-31457

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-31457 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-31457

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/3527e9fdc38570cea0f6ddb7a2c9303d4044b217

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/652cd0641a763dd0e846b0d12814977fadb2b7d8

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/6557004a8b59c7701e695f02be03c7e20ed1cc15

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.