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CVE-2026-31456 Linux CVE debrief

A race condition vulnerability was discovered in the Linux kernel, specifically in the `walk_pud_range()` function. This vulnerability occurs when a PUD entry is being split concurrently with a refault operation on the PUD leaf entry. This can lead to a kernel BUG and potentially allow an attacker to crash the system. The vulnerability has a CVSS score of 4.7 and is classified as MEDIUM severity.

Vendor
Linux
Product
Unknown
CVSS
MEDIUM 4.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-22
Original CVE updated
2026-06-17
Advisory published
2026-04-22
Advisory updated
2026-06-17

Who should care

Users of Linux kernel versions 6.12, 6.19, and 7.0 (up to rc5) should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability is caused by a race condition between concurrent split and refault operations in the `walk_pud_range()` function. This can lead to a kernel BUG and potentially allow an attacker to crash the system. The fix involves validating the PUD entry in `walk_pmd_range()` using a stable snapshot (`pudp_get()`).

Defensive priority

MEDIUM

Recommended defensive actions

  • Apply the patches provided by the Linux kernel maintainers [ref-4], [ref-5], [ref-6].
  • Update to a Linux kernel version that includes the fix, such as 6.18.21, 6.19.11, or later.

Evidence notes

The vulnerability was discovered and reported by an unknown researcher. The fix was provided by the Linux kernel maintainers.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-31456 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-31456

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

  • CVE-2026-31456 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-31456

    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/38ec58670a0c5fc1edabdeccd857e586b7b3f318

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

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/3b89863c3fa482912911cd65a12a3aeef662c250

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

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/9bbbebd94dd5be25ec8c899d46ef01b33d5d22c0

    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.