CVE-2026-64177 Linux CVE debrief

Who should care

Linux kernel users and maintainers should be aware of this vulnerability and ensure they apply the necessary patches to prevent potential issues. This includes reviewing and updating Linux kernel configurations to ensure the fix is applied and monitoring system logs for potential issues related to this vulnerability. Additionally, operators, platform administrators, and security teams may need to assess their exposure and take appropriate measures to mitigate the risk.

Technical summary

The Linux kernel vulnerability CVE-2026-64177 was caused by the inconsistent lock state of the child socket's slock, which was acquired with BH on in process context and with BH off in softirq context. This inconsistency could lead to a potential self-deadlock if a softirq on the same CPU tries to receive to the same child socket while its slock is held in the BH-enabled path. The fix involves disabling BH around forwarded sk_receive_skb() to prevent this inconsistent lock state and potential self-deadlock. The vulnerability was discovered via in-house syzkaller fuzzing and also reported on the linux-6.1.y syzbot dashboard.

Defensive priority

Medium

Recommended defensive actions

• Apply the official patch to disable BH around forwarded sk_receive_skb()
• Review and update Linux kernel configurations to ensure the fix is applied
• Monitor system logs for potential issues related to this vulnerability
• Perform a thorough review of affected systems to identify potential exposure
• Consider implementing compensating controls for exposed systems while remediation is scheduled and verified
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Review relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The vulnerability was discovered via in-house syzkaller fuzzing and also reported on the linux-6.1.y syzbot dashboard. The fix was applied to the Linux kernel to prevent inconsistent lock state and potential self-deadlock. Evidence of the vulnerability includes the inconsistent lock state warning and potential self-deadlock. Defenders should verify that the necessary patches have been applied and review system logs for potential issues related to this vulnerability.

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.