CVE Catalog

CVE-2026-97939

Unknown
Published: Translated: NVD NIST

Summary

In the Linux kernel, the ipmr subsystem lacks memory accounting for multicast tables and routes. A netadmin in a user+net namespace can create many multicast routing tables that are not charged to memcg, leading to uncontrolled growth of unreclaimable slab memory.

Risk Assessment

This can lead to memory exhaustion on the host, impacting the stability and availability of all services running on that host.

Recommendation

Apply the kernel patch that adds memory accounting for mr_table and marks MFC caches as SLAB_ACCOUNT to limit memory usage.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: ipmr: account multicast table and route memory A netadmin in a user+net namespace can create many IPv4 and IPv6 multicast routing tables with MRT_TABLE and MRT6_TABLE. Each unseen id allocates an mr_table via the shared mr_table_alloc(), links it into the per-net list, and leaves it until netns teardown. Those objects were not charged to memcg, so the host unreclaimable slab grows with the table count. Account mr_table allocations with GFP_KERNEL_ACCOUNT and mark the IPv4/IPv6 MFC caches SLAB_ACCOUNT. This matches the established handling of IP addresses, routes and alternate interface names. Unresolved MFC entries are still allocated from softIRQ with GFP_ATOMIC and are not charged. They expire after 10 seconds and are bounded by the socket receive queue; see commit 0079ad8e8dc3 ("ipmr: remove hard code cache_resolve_queue_len limit").

Vulnerability data from NVD (NIST) · CISA KEV · EPSS