CVE-2026-52946 Linux CVE debrief

Who should care

Linux kernel users and administrators should be aware of this vulnerability, as it can be exploited remotely to cause a denial of service. System administrators and security teams should prioritize patching and monitoring their Linux kernel installations. Additionally, developers and maintainers of Linux kernel-based systems should review the patch and apply it to their systems.

Technical summary

The vulnerability is caused by a SOFTIRQ-safe to SOFTIRQ-unsafe lock order deadlock in send_sigio() and send_sigurg() when a process group receives a signal. The deadlock occurs due to the rwlock writer fairness mechanism, where a process holding a read lock in do_wait() can be interrupted by a softirq, leading to a deadlock. The fix replaces tasklist_lock with rcu_read_lock(), aligning the process group signaling path with the single-PID path. This change mitigates a potential remote denial of service vector via TCP URG packets. The vulnerability has a CVSS score of 7.5 and is classified as HIGH-severity.

Defensive priority

High priority should be given to patching and monitoring Linux kernel installations, as this vulnerability can be exploited remotely to cause a denial of service. System administrators and security teams should review the patch and apply it to their systems as soon as possible.

Recommended defensive actions

• Patch Linux kernel installations with the provided fix.
• Monitor Linux kernel installations for signs of exploitation.
• Review system logs for potential denial of service attempts.
• Apply compensating controls, such as network segmentation and access controls, to mitigate potential attacks.
• Track and update Linux kernel installations to ensure timely patching of future vulnerabilities.

Evidence notes

The vulnerability was published on June 24, 2026, and modified on June 28, 2026. The CVSS score is 7.5, and the severity is classified as HIGH. The vulnerability involves a SOFTIRQ-unsafe lock order in fasync signaling, which can cause a deadlock when a process group receives a signal. The fix replaces tasklist_lock with rcu_read_lock(), aligning the process group signaling path with the single-PID path.

Official resources