The vulnerability arises when a netadmin in a user+network namespace can create an arbitrary number of IPv4 or IPv6 multicast routing tables using MRT_TABLE and MRT6_TABLE. Each newly created table allocates an mr_table via mr_table_alloc, which is then linked to the per-net list. Because these objects are not accounted to the memory control group, unreclaimable slab memory grows with the number of tables, potentially exhausting system memory. This uncontrolled resource consumption can lead to a denial‑of‑service condition, degrading overall system availability. The flaw typifies an uncontrolled resource consumption weakness (CWE‑400).

The flaw exists in all Linux kernel releases that implement the legacy multicast table allocation logic before the commits referenced in the provided git URLs. Distributions shipping a kernel version prior to those commits are affected. The mechanism is part of the core kernel, not tied to a specific distribution build.

Exploitation requires a user with netadmin privileges inside a network namespace, so the primary attack vector is a local privileged netadmin user within a network namespace. The vulnerability is not remotely exploitable and is unlikely to be targeted from outside. The EPSS score is < 1%, and the CVSS score is 5.5. The vulnerability is not listed in the CISA KEV catalog, but because the unchecked allocation can continually grow slab memory, it poses a moderate‑severity risk that could disrupt services or lead to system unavailability. Once the conditions are met, the kernel will allocate additional mr_tables until memory is depleted or the system becomes unstable.