Microsoft security update for CVE-2025-68214 — azl3 kernel 6.6.117.1-1 on Azure Linux 3.0
🔗 CVE IDs covered (1)
📋 Microsoft's advisory
EchelonGraph does not copy Microsoft's advisory page: its FAQ and remediation text are not shown here. Read the advisory on https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-68214. This page also shows what EchelonGraph holds for CVE-2025-68214, with the description from its CVE record, which the CVE Numbering Authority that assigned the CVE wrote: for a CVE Microsoft assigned, often in the words of Microsoft's own advisory.
🎯 Affected products1
- azl3 kernel 6.6.117.1-1 on Azure Linux 3.0
✅ Updates Microsoft lists: 1 update
1 row: one per KB article or update, update type and fixed build. Their details are on Microsoft's advisory.
| KB article | Update | Fixed build |
|---|---|---|
| — | Security Update | 6.6.119.3-1 |
🧭 EchelonGraph on CVE-2025-68214
- EchelonGraph score
- 4.7 MEDIUM
- CISA KEV
- Not listed
- Fix status
- A fix is available — apply it.
Description from the CVE record (CVE.org), as published by its numbering authority
In the Linux kernel, the following vulnerability has been resolved: timers: Fix NULL function pointer race in timer_shutdown_sync() There is a race condition between timer_shutdown_sync() and timer expiration that can lead to hitting a WARN_ON in expire_timers(). The issue occurs when timer_shutdown_sync() clears the timer function to NULL while the timer is still running on another CPU. The race scenario looks like this: CPU0 CPU1 <SOFTIRQ> lock_timer_base() expire_timers() base->running_timer = timer; unlock_timer_base() [call_timer_fn enter] mod_timer() ... timer_shutdown_sync() lock_timer_base() // For now, will not detach the timer but only clear its function to NULL if (base->running_timer != timer) ret = detach_if_pending(timer, base, true); if (shutdown) timer->function = NULL; unlock_timer_base() [call_timer_fn exit] lock_timer_base() base->running_timer = NULL; unlock_timer_base() ... // Now timer is pending while its function set to NULL. // next timer trigger <SOFTIRQ> expire_timers() WARN_ON_ONCE(!fn) // hit ... lock_timer_base() // Now timer will detach if (base->running_timer != timer) ret = detach_if_pending(timer, base, true); if (shutdown) timer->function = NULL; unlock_timer_base() The problem is that timer_shutdown_sync() clears the timer function regardless of whether the timer is currently running. This can leave a pending timer with a NULL function pointer, which triggers the WARN_ON_ONCE(!fn) check in expire_timers(). Fix this by only clearing the timer function when actually detaching the timer. If the timer is running, leave the function pointer intact, which is safe because the timer will be properly detached when it finishes running.
Published by kernel.org, the CVE Numbering Authority that assigned CVE-2025-68214, in its CVE record at CVE.org; reused under the CVE Program's Terms of Use (its licence and MITRE's copyright notice are in our Terms of Service).