CVE-2026-23419 Linux CVE debrief

Who should care

System administrators and security teams responsible for Linux kernel-based systems, particularly those using kernel versions prior to the patched versions, should be aware of this vulnerability and take necessary actions to mitigate the risk.

Technical summary

The vulnerability is caused by a circular locking dependency in the rds_tcp_tune function of the Linux kernel. The function calls sk_net_refcnt_upgrade() while holding the socket lock, which leads to a dependency with fs_reclaim. To fix this issue, the sk_net_refcnt_upgrade() call has been moved outside the socket lock critical section. This change ensures that the fields modified by sk_net_refcnt_upgrade() are not accessed by any concurrent code path at that point.

Defensive priority

High

Recommended defensive actions

• Apply the official patches provided by the Linux kernel maintainers.
• Ensure that the Linux kernel is updated to a version that includes the fix, such as 5.18.1 or later, 6.6.130 or later, 6.7 or later, 6.12.77 or later, 6.13 or later, 6.18.17 or later, 6.19 or later, or 6.19.7 or later.
• Monitor system logs for potential exploitation attempts.
• Implement compensating controls, such as network segmentation and access controls, to limit the attack surface.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The vulnerability was reported by syzbot and has been resolved by the Linux kernel maintainers. The fix involves moving the sk_net_refcnt_upgrade() call outside the socket lock critical section. The affected kernel versions and patched versions are documented in the CVE record and NVD entry.

Official resources