CVE-2026-90327 Linux CVE debrief

Who should care

Linux kernel maintainers, administrators, and users should assess exposure and prioritize patching. Linux kernel exposure can lead to potential data corruption or information disclosure due to improper getsockopt handling, and possible denial of service due to unexpected behavior.

Why it matters

Linux kernel vulnerability in phonet: pep: do not write beyond optlen in getsockopt. Assess Linux kernel exposure, prioritize patching, and monitor for potential exploitation attempts.

• Potential data corruption or information disclosure due to improper getsockopt handling
• Possible denial of service due to unexpected behavior

Technical summary

The Linux kernel has a vulnerability in the phonet: pep: do not write beyond optlen in getsockopt. The pep_getsockopt() function clamps the reported length to the caller's buffer, but then stores the value with put_user(val, (int __user *) optval), which always writes sizeof(int) bytes. A getsockopt() call with an optlen smaller than sizeof(int) thus reports the clamped length yet writes a full int, one to three bytes past the user buffer.

Defensive priority

Assess Linux kernel exposure, prioritize patching

Recommended defensive actions

• Assess Linux kernel exposure and prioritize patching
• Review and apply Linux kernel patches
• Monitor Linux kernel for potential exploitation attempts
• 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

Official CVE Program record and NVD vulnerability detail page provide information on the vulnerability. Linux kernel commit records provide patch details. The CVE record was published on 2026-09-17T16:08:42.017Z and has not been modified since then. The NVD vulnerability detail page provides additional information on the vulnerability, including its CVSS score and severity.

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.