UBUNTU-CVE-2026-99237: High severity ubuntu/linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: tracing: Hold tracetypeslock when resetting last boot data from readers updatelastdataifempty() is called from tracingopen() with OTRUNC, tracingreadpipe() and tracingbuffersread() without tracetypeslock. Two readers can both pass the LASTBOOT test and free moduledelta twice, and a module notifier can update moduledelta while it is being freed. Take tracetypeslock in those paths and keep the callers that already hold it on an unlocked variant.
Affected Software
Event History
Frequently Asked Questions
Which Ubuntu systems are exposed?
Systems using the listed Ubuntu kernel packages may be affected: linux, linux-fips, linux-aws, linux-azure, linux-gcp, linux-oracle, linux-aws-fips, and linux-azure-fips. The issue is in Linux kernel tracing paths.
What access does an attacker need to exploit this?
The supplied severity vector indicates local access, low attack complexity, low privileges, and no user interaction are required. Successful exploitation can affect confidentiality, integrity, and availability.
What conditions trigger the race?
The race involves concurrent readers resetting last-boot tracing data, including tracing opens using O_TRUNC and reads through tracing_read_pipe() or tracing_buffers_read(). Concurrent activity can cause module_delta to be freed twice or modified while it is being freed.
What is the remediation described by the fix?
The fix holds trace_types_lock while resetting last-boot data in the affected reader paths, while retaining an unlocked helper for callers that already hold the lock.