CVE-2026-98611 bpf: Check params size before reading reserved fields
A local attacker with BPF privileges can read kernel memory beyond validated bounds due to missing size checks in bpf_crypto_ctx_create.
- 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-2026-98611?
CVE-2026-98611 is a vulnerability in Linux, published on 18 Oct 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: Check params size before reading reserved fields
bpf_crypto_ctx_create() is a kfunc whose second argument is declared with the __sz annotation, so the verifier only guarantees that params__sz bytes of params are valid. The function nevertheless reads params->reserved[0] and params->reserved[1] (offsets 14 and 15) before comparing params__sz against the size of struct bpf_crypto_params, so a BPF program can pass a shorter buffer and have the kernel read past the region that was validated for it.
Move the size check in front of the reserved field reads.
Which versions are affected by CVE-2026-98611?
How do I fix CVE-2026-98611?
Apply the vendor's patch.
Is CVE-2026-98611 being exploited?
There is no known exploitation of CVE-2026-98611 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98611, DEBIAN-CVE-2026-98611, GHSA-3j3q-mxmx-xwq4, UBUNTU-CVE-2026-98611.