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PatchSiren cyber security CVE debrief

CVE-2026-31496 Linux CVE debrief

A MEDIUM severity vulnerability was found in the Linux kernel, with a CVSS score of 5.5. The vulnerability has been resolved in the netfilter component. This issue allows attackers to skip expectations that do not reside in the current network namespace via proc. Users of the Linux kernel, particularly those using versions prior to the patched versions, should be aware of this vulnerability and take steps to mitigate it. The vulnerability was resolved by skipping expectations that do not reside in the current network namespace via proc.

Vendor
Linux
Product
Unknown
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-14
Original CVE updated
2026-07-28
Advisory published
2026-07-14
Advisory updated
2026-07-28

Who should care

Users of the Linux kernel, particularly those using versions prior to the patched versions, should be aware of this vulnerability and take steps to mitigate it. System administrators and security teams responsible for Linux kernel-based systems should review their system configurations and apply patches from Linux kernel maintainers. Additionally, users should monitor for suspicious network activity and implement compensating controls for netfilter.

Technical summary

The vulnerability is related to the netfilter component of the Linux kernel. The issue was resolved by skipping expectations that do not reside in the current network namespace via proc. This change prevents attackers from accessing and manipulating network connections outside of their current network namespace. The vulnerability has been patched, and users are advised to apply patches from Linux kernel maintainers.

Defensive priority

Medium priority, as the vulnerability has been patched and CVSS score is 5.5

Recommended defensive actions

  • Inventory and verify Linux kernel versions
  • Apply patches from Linux kernel maintainers
  • Monitor for suspicious network activity
  • Implement compensating controls for netfilter
  • Review system configurations for potential vulnerabilities
  • Track exceptions and retest remediated assets
  • Verify patch deployment and system security posture

Evidence notes

The CVE record was published on 2026-04-22T14:16:47.693Z and last modified on 2026-07-14T13:18:43.560Z. The NVD entry is currently Modified. This vulnerability affects Linux kernel versions prior to the patched versions. Users should verify their system configurations and apply patches from Linux kernel maintainers. The CVE record provides limited information on the vulnerability's scope and impact.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-31496 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-31496

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

  • CVE-2026-31496 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-31496

    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/168145c87444619e3e649322bbe7719ecd00d411

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

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/2028405ea6987b4448784e439413202cfe19f43f

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

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/3265ad619987cb551edaf797ed056d80ac450225

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

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/3db5647984de03d9cae0dcddb509b058351f0ee4

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

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/9ca8c7452493d915f9bbf2f39331e6c583d07a23

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

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/dcfcd95b3ae7683e8ae55c92284b3430ce614bc7

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

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-019113.html

    0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

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.