CVE-2026-31671 Linux CVE debrief

Who should care

Linux kernel developers, Linux distribution maintainers, and users of Linux-based systems should be aware of this vulnerability. This vulnerability may allow local attackers to gain sensitive information about the system's kernel state. Operators of Linux-based systems, platform administrators, vulnerability management teams, and security teams should review their exposure and take necessary actions to mitigate the vulnerability.

Technical summary

The Linux kernel's xfrm_user module has a vulnerability that causes an info leak in the build_report() function. The xfrm_user_report structure has padding bytes that are not zeroed out before being copied to userspace. This leads to the disclosure of sensitive information. The vulnerability has been resolved by zeroing out the structure before setting individual member variables. Affected Linux kernel versions should be updated to ensure the fix is applied. The vulnerability can be mitigated by applying patches or updates provided by the Linux kernel maintainers and reviewing Linux kernel versions to ensure the fix is applied.

Defensive priority

Apply patches or updates provided by the Linux kernel maintainers to fix the vulnerability. Review and update Linux kernel versions to ensure the fix is applied. Monitor Linux kernel updates and patches for future vulnerabilities.

Recommended defensive actions

• Apply patches or updates provided by the Linux kernel maintainers to fix the vulnerability.
• Review and update Linux kernel versions to ensure the fix is applied.
• Monitor Linux kernel updates and patches for future vulnerabilities.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record was published on 2026-04-24T15:16:46.903Z and was last modified on 2026-07-14T13:18:48.083Z. The NVD entry is currently Modified. This vulnerability affects the Linux kernel's xfrm_user module, specifically in the build_report() function, where sensitive information can be leaked due to uninitialized padding bytes in the xfrm_user_report structure. To verify and mitigate this vulnerability, defenders should review the official CVE record and NVD details, assess their Linux kernel versions for exposure, and apply patches or updates provided by the Linux kernel maintainers. Evidence of exposure can be found in system logs related to xfrm_user module activities.

Sources and references

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.