CVE-2026-63825

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description An issue exists in the Linux kernel where GCC's GCOV instrumentation may merge global branch counters with loop induction variables as an optimization. In the inflate fast() function, the GCOV counter value is loaded multiple times to compute the loop base address, start index, and end bound. Because GCOV counters are global and not per-CPU, concurrent execution on different CPUs can cause the counter to change between these loads. This leads to inconsistent values and out-of-bounds memory writes, resulting in a system crash during IP Payload Compression (IPComp) processing.

Recommendations Add -fprofile-update=prefer-atomic to CFLAGS GCOV in the top-level Makefile, ensuring it is guarded by a try-run compile test to avoid introducing libatomic dependencies on unsupported architectures.