CVE-2026-74364 bpf: Reject exclusive maps as inner maps in map-in-map
Attackers can bypass BPF map exclusivity checks by nesting exclusive maps in outer maps, allowing unauthorized modification of protected data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74364?
CVE-2026-74364 is a high-severity vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
bpf: Reject exclusive maps as inner maps in map-in-map
An exclusive map (created with excl_prog_hash) is bound to a single program by hash: check_map_prog_compatibility() refuses to load any program whose digest does not match map->excl_prog_sha. That check only runs for maps a program references directly, i.e. its used_maps. A map reached at runtime through a map-of-maps is never in used_maps, and bpf_map_meta_equal() does not consider excl_prog_sha, so an exclusive map can be inserted into a non-exclusive outer map and then looked up and mutated by an unrelated program, bypassing the exclusivity guarantee.
For the signed loader this defeats the metadata map exclusivity check added in the signed loader: the cached map->sha[] is validated against the signed hash while another program on a hostile host rewrites the frozen map's contents through the outer map.
Which versions are affected by CVE-2026-74364?
How do I fix CVE-2026-74364?
Apply the vendor's patch.
Is CVE-2026-74364 being exploited?
There is no known exploitation of CVE-2026-74364 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74364, DEBIAN-CVE-2026-74364, GHSA-723q-c22r-gxfr, UBUNTU-CVE-2026-74364.