CVE-2026-31574: 
Linux Kernel vulnerability analysis and mitigation

CVE-2026-31574 is a Linux kernel vulnerability in the clockevents subsystem caused by missing resets of the next_event_forced flag, which can lead to timer interrupt starvation and system stalls. The flaw affects Linux kernel versions up to (but not including) 7.0.1, with the kernel 7.0 release confirmed as vulnerable. It was published on April 24, 2026, and carries a CVSS v3.1 base score of 5.5 (Medium) (GitHub Advisory, Red Hat Bugzilla).

The root cause is classified as CWE-821 (Incorrect Synchronization) — the next_event_forced flag in the Linux kernel's clockevents subsystem is not properly reset in three critical code paths: (1) when the clock event state changes, leaving the flag stale across shutdown/startup sequences; (2) when a non-forced event is armed, which incorrectly prevents rearming and causes missed timer interrupts if the event is scheduled far in the future; and (3) in the suspend wakeup handler. Exploitation requires local access with low privileges, as an attacker or process triggering these state transitions could cause the flag to retain an incorrect value, leading to timer interrupt starvation. Patches are available at the upstream kernel repository (GitHub Advisory, Red Hat Bugzilla).

The primary impact is a high availability risk: missed timer interrupts caused by the stale next_event_forced flag result in system stalls and hangs, particularly on systems undergoing clock event state transitions, suspend/resume cycles, or scheduling events far into the future. There is no confidentiality or integrity impact. The vulnerability affects all Linux systems running kernel versions prior to 7.0.1 and has been confirmed to cause real-world stalls reported by multiple users (GitHub Advisory).

There is no known public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time (GitHub Advisory). The EPSS score is approximately 0.018% (6th percentile), indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires local access with low privileges, limiting the attack surface primarily to multi-tenant or shared environments.

The fix is available in Linux kernel version 7.0.1, which adds the missing next_event_forced flag resets in the affected clockevents code paths. Administrators should update to kernel 7.0.1 or later as soon as possible. As a temporary measure, avoiding frequent suspend/resume cycles or clock event state transitions on affected systems may reduce the likelihood of triggering the stall condition. Detection is available via Nessus plugin 310312 and Qualys detection ID 918245 (GitHub Advisory, Red Hat Bugzilla).

Red Hat has tracked this issue via their Security Response process (Bugzilla Bug 2461508) and assigned it medium priority and severity. The Yocto Project security mailing list has also discussed the vulnerability across multiple messages, indicating awareness in the embedded Linux community (Red Hat Bugzilla). No significant broader media coverage or notable researcher commentary has been identified beyond standard vulnerability tracking.