CVE-2025-38499: Debian Linux

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: clone_private_mnt(): make sure that caller has CAP_SYS_ADMIN in the right userns What we want is to verify there is that clone won't expose something hidden by a mount we wouldn't be able to undo. "Wouldn't be able to undo" may be a result of MNT_LOCKED on a child, but it may also come from lacking admin rights in the userns of the namespace mount belongs to. clone_private_mnt() checks the former, but not the latter. There's a number of rather confusing CAP_SYS_ADMIN checks in various userns during the mount, especially with the new mount API; they serve different purposes and in case of clone_private_mnt() they usually, but not always end up covering the missing check mentioned above.

Affected products

• Debian Debian Linux: version 11.0 only
• Linux Linux Kernel: from 4.4.281, before 4.5 (fixed in 4.5); from 4.9.280, before 4.10 (fixed in 4.10); from 4.14.244, before 4.15 (fixed in 4.15); from 4.19.204, before 4.20 (fixed in 4.20); from 5.4.141, before 5.5 (fixed in 5.5); from 5.10.59, before 5.11 (fixed in 5.11); …

Published 2025-08-11. Last modified 2026-07-30.