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PatchSiren cyber security CVE debrief

CVE-2026-53081 Linux CVE debrief

CVE-2026-53081 is a high-severity vulnerability in the Linux kernel, with a CVSS score of 7.8. The vulnerability is related to BPF (Berkeley Packet Filter) and specifically deals with the enforcement of regsafe base id consistency for BPF_ADD_CONST scalars. The issue arises when the verifier compares two scalar registers carrying BPF_ADD_CONST, allowing for the construction of verifier states that can lead to incorrect state pruning. This vulnerability has been resolved by enforcing additional verification of base ID mapping consistency when BPF_ADD_CONST is set.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-24
Original CVE updated
2026-07-06
Advisory published
2026-06-24
Advisory updated
2026-07-06

Who should care

This vulnerability affects Linux kernel users and maintainers. Given its high severity, organizations using Linux kernels should assess their exposure and apply patches or mitigations as necessary. Linux distribution maintainers and kernel developers should prioritize patching and notifying users.

Technical summary

The vulnerability is in the Linux kernel's BPF subsystem, specifically in the regsafe() function that compares scalar registers with BPF_ADD_CONST. The problem is that it doesn't verify the consistency of the underlying base IDs when BPF_ADD_CONST is set. This oversight allows for the creation of verifier states that can bypass intended safety checks, potentially leading to security issues. The fix involves ensuring that base ID mappings are consistent when BPF_ADD_CONST is applied.

Defensive priority

High priority should be given to patching affected Linux kernels. Organizations should review their kernel versions and apply patches or updates provided by their distribution or the Linux kernel community.

Recommended defensive actions

  • Review and apply patches for the Linux kernel related to BPF_ADD_CONST scalars.
  • Assess the exposure of Linux kernel deployments within your organization.
  • Monitor Linux distribution advisories for CVE-2026-53081 patches.
  • Consider compensating controls or mitigations if patching is not immediately feasible.
  • Verify the integrity of kernel updates before deployment.
  • Update incident response plans to account for potential exploitation.

Evidence notes

The CVE-2026-53081 record and associated details were obtained from the CVE.org and NVD databases. Additional information was derived from Linux kernel patch references. Evidence suggests this is a high-severity issue affecting the Linux kernel's BPF subsystem.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-53081 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-53081

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

  • CVE-2026-53081 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-53081

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

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/13c02881e49aac4c82b261faa26db9edf2567231

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/2f2ec8e7730e21fc9bd49e0de9cdd58213ea24d0

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/691adf738817275368ed56311b7d798d617823a3

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/7d73c72cccac651acc891377a5e623e4021c6380

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

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.