CVE-2026-93138 bpf: Fix vmlinux BTF prep race in bpf_get_btf_vmlinux
A race condition in Linux kernel BPF handling allows attackers to potentially execute arbitrary code or escalate privileges via memory corruption.
- 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-2026-93138?
CVE-2026-93138 is a high-severity vulnerability in Linux, published on 17 Sep 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: Fix vmlinux BTF prep race in bpf_get_btf_vmlinux
bpf_get_btf_vmlinux() lazily parses the vmlinux BTF under the bpf_verifier_lock, but publishes the result through a plain store and re-checks it through a plain lockless load. Nothing orders the stores initializing the struct btf inside btf_parse_vmlinux() against the store publishing the pointer: On a weakly ordered arch, a concurrent first-time caller taking the lockless fast path could in principle observe the pointer before the parsed contents are visible. The mutex_unlock() does not help such a reader given it only synchronizes with a later acquisition of the same lock. Thus, publish the pointer with smp_store_release() and read it on the fast path with smp_load_acquire().
Acquire semantics are needed rather than a dependency-ordered READ_ONCE(): btf_parse_vmlinux() also populates globals outside the returned object (e.g. bpf_ctx_convert.t). An address dependency would only order accesses performed through the pointer and not cover other globals.
Which versions are affected by CVE-2026-93138?
How do I fix CVE-2026-93138?
Apply the vendor's patch.
Is CVE-2026-93138 being exploited?
There is no known exploitation of CVE-2026-93138 in the wild and no public exploit code.
Sources
Also known as AZL-102888, BELL-CVE-2026-93138, DEBIAN-CVE-2026-93138, GHSA-j9m2-mp7m-3w46, UBUNTU-CVE-2026-93138.