CVE-2026-64004 Linux CVE debrief

Who should care

System administrators and users of Linux kernel versions affected by this vulnerability should be aware of the potential impact and take necessary actions to mitigate the risk. They should review the official advisory and apply the patch or update to a fixed Linux kernel version. Additionally, they should monitor system logs for potential exploitation attempts and implement compensating controls, such as limiting access to the affected system.

Technical summary

The vulnerability is caused by a locking issue in the .getsockopt function of the net/iucv component in the Linux kernel. Specifically, the SO_MSGSIZE arm dereferences iucv->hs_dev->mtu after iucv_sock_close() has set hs_dev to NULL, producing a NULL pointer dereference oops. This can be exploited by an AF_IUCV HIPER user racing recvmsg() with getsockopt(SO_MSGSIZE). The vulnerability affects Linux kernel versions and can be mitigated by applying the official patch or updating to a fixed Linux kernel version.

Defensive priority

High

Recommended defensive actions

• Apply the official patch or update to a fixed Linux kernel version.
• Monitor system logs for potential exploitation attempts.
• Implement compensating controls, such as limiting access to the affected system.
• Review the official advisory to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• 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.

Evidence notes

The CVE record was published on 2026-07-19T16:17:40.043Z and has not been modified since then. The NVD entry is currently Received. There is limited information available about the vulnerability, and defenders should verify the affected scope and severity with the official advisory. The Linux kernel's net/iucv component is affected, and the issue is related to locking in the .getsockopt function.

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.