The mac80211_hwsim driver in the Linux kernel has a race condition that can trigger the WARN_ON(!local->started) assertion after a simulated radio is stopped while frames are pending delivery. This flaw, classified as CWE-367, leads to a kernel warning that signals an internal inconsistency but does not directly cause remote code execution or privilege escalation.

Linux kernel builds that include the mac80211_hwsim driver are affected. The vulnerability exists in any kernel version that predates the commits referenced in the advisory. Users of the hwsim simulator—common in continuous integration pipelines, automated testing, and educational environments—are the primary impact set. Kernel deployments that do not load the mac80211_hwsim module are not impacted.

The CVSS score of 5.5 and an EPSS score of less than 1% appear in the data, and the issue is not listed in CISA’s KEV catalog. The flaw requires a scenario where a simulated radio is started, frames are queued, and then the radio is stopped, an event typically driven by a local or controlled environment such as test harnesses. Consequently, the likelihood of exploitation in typical production systems is low, but the presence of a kernel warning still warrants a timely patch.