CVE-2026-74483

A flaw was found in the binfmt_misc component of the Linux kernel. An unprivileged local attacker, operating under specific memory constraints (a tight memory cgroup), could repeatedly trigger a failure in the bm_fill_super() function during a mount operation. This failure prevents the proper release of a user namespace reference, leading to a leak of one user namespace per attempt. This resource exhaustion can result in a denial of service (DoS) for the system.

This vulnerability is rated as Low severity because exploitation requires local access, user namespace privileges, and finely tuned memory limitations, resulting strictly in gradual resource consumption rather than unauthorized access or code execution. An attacker must repeatedly induce kernel allocation failures during unprivileged filesystem mounting to trigger the user namespace reference leak, which slowly degrades system memory availability until a denial of service occurs. Furthermore, enterprise distributions such as Red Hat Enterprise Linux 8 and 9 lack the underlying per-namespace binfmt_misc architecture and are not vulnerable to this condition.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.