CVE-2026-74660

A flaw was found in the Linux kernel's netfilter: ebt_nflog component. This vulnerability occurs because the ebt_nflog module does not properly manage references to the nfnetlink_log module. An attacker with the ability to configure ebtables rules could exploit this by causing an ebtables nflog rule to remain active while the nfnetlink_log module is unloaded. This improper handling leads to a use-after-free error, which can result in a system crash, causing a Denial of Service (DoS).

ebt_nflog can call the NFLOG backend without holding a module reference, so an ebtables NFLOG rule may remain callable while nfnetlink_log is being unloaded. During this race the per net nfnetlink_log state can be freed by module teardown while the packet path still reaches nfulnl_log_packet() and instance_lookup_get_rcu(), producing a slab use after free. For the CVSS the PR:L is used for the paranoid score because some environments delegate netfilter control or module lifecycle to service accounts or reduced capability root, while a stricter base score uses PR:H. The issue is not directly network reachable because packet traffic alone does not unload the backend, but network or local packets can hit the vulnerable rule during the local teardown window. Impact is at least local denial of service via kernel crash and in the worst defensible case may include confidentiality or integrity impact due to kernel use after free, so it should be reviewed manually.

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.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.