CVE-2025-38067: Debian Linux

Medium severity, CVSS 5.5. EPSS: 0.6% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: rseq: Fix segfault on registration when rseq_cs is non-zero The rseq_cs field is documented as being set to 0 by user-space prior to registration, however this is not currently enforced by the kernel. This can result in a segfault on return to user-space if the value stored in the rseq_cs field doesn't point to a valid struct rseq_cs. The correct solution to this would be to fail the rseq registration when the rseq_cs field is non-zero. However, some older versions of glibc will reuse the rseq area of previous threads without clearing the rseq_cs field and will also terminate the process if the rseq registration fails in a secondary thread. This wasn't caught in testing because in this case the leftover rseq_cs does point to a valid struct rseq_cs. What we can do is clear the rseq_cs field on registration when it's non-zero which will prevent segfaults on registration and won't break the glibc versions that reuse rseq areas on thread creation.

Affected products

• Debian Debian Linux: version 11.0 only
• Linux Linux Kernel: from 4.18, before 5.10.240 (fixed in 5.10.240); from 5.11, before 5.15.189 (fixed in 5.15.189); from 5.16, before 6.1.146 (fixed in 6.1.146); from 6.2, before 6.6.99 (fixed in 6.6.99); from 6.7, before 6.12.39 (fixed in 6.12.39); from 6.13, before 6.14.9 (fixed in 6.14.9)

Published 2025-06-18. Last modified 2026-06-17.