CVE-2026-74344 bpf: Clear rb node linkage when freeing bpf_rb_root
A use-after-free in the Linux kernel BPF subsystem allows attackers to corrupt memory and potentially execute arbitrary code or escalate privileges.
- 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-2026-74344?
CVE-2026-74344 is a high-severity use after free 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: Clear rb node linkage when freeing bpf_rb_root
bpf_rb_root_free() detaches the root by copying the current rb_root_cached and then replacing the live root with RB_ROOT_CACHED. It then walks the copied root and drops each object contained in the tree.
This leaves the rb node state intact while dropping the object. If the object is refcounted and survives the drop, its bpf_rb_node_kern still contains an owner pointer to the freed root and stale rb tree linkage. If a later bpf_rb_root allocation reuses the same address, bpf_rbtree_remove() can incorrectly pass the owner check and call rb_erase_cached() on a node whose rb pointers belong to the old tree.
Mirror the list draining behavior by marking nodes as busy while the root is being detached, then clear the rb node and release the owner before dropping the containing object. This makes surviving nodes unowned and safe to reject from remove or accept for a later add.
Which versions are affected by CVE-2026-74344?
How do I fix CVE-2026-74344?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-74344 being exploited?
There is no known exploitation of CVE-2026-74344 in the wild and no public exploit code.
Sources
Also known as AZL-96288, BELL-CVE-2026-74344, DEBIAN-CVE-2026-74344, GHSA-345m-8q8p-cx77, UBUNTU-CVE-2026-74344.