Summary
In the Linux kernel, the following vulnerability has been resolved: comedi: fix race between...
In the Linux kernel, the following vulnerability has been resolved:
comedi: fix race between polling and detaching
syzbot reports a use-after-free in comedi in the below link, which is
due to comedi gladly removing the allocated async area even though poll
requests are still active on the wait_queue_head inside of it. This can
cause a use-after-free when the poll entries are later triggered or
removed, as the memory for the wait_queue_head has been freed. We need
to check there are no tasks queued on any of the subdevices' wait queues
before allowing the device to be detached by the COMEDI_DEVCONFIG
ioctl.
Tasks will read-lock dev->attach_lock before adding themselves to the
subdevice wait queue, so fix the problem in the COMEDI_DEVCONFIG ioctl
handler by write-locking dev->attach_lock before checking that all of
the subdevices are safe to be deleted. This includes testing for any
sleepers on the subdevices' wait queues. It remains locked until the
device has been detached. This requires the comedi_device_detach()
function to be refactored slightly, moving the bulk of it into new
function comedi_device_detach_locked().
Note that the refactor of comedi_device_detach() results incomedi_device_cancel_all() now being called while dev->attach_lock
is write-locked, which wasn't the case previously, but that does not
matter.
Thanks to Jens Axboe for diagnosing the problem and co-developing this
patch.
Impact
Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing. Typical impact: TOCTOU exploits, data corruption, or privilege escalation.
CVE-2025-38687 has a CVSS score of 4.7 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-38687? CVE-2025-38687 is a medium-severity race condition vulnerability. No fixed version is listed yet. Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing.
- How severe is CVE-2025-38687? CVE-2025-38687 has a CVSS score of 4.7 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2025-38687? No fixed version is listed for CVE-2025-38687 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-38687 exploitable, and should I be worried? Whether CVE-2025-38687 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-38687 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.