CVE-2026-90157 bpf: Reject negative optlen in cgroup getsockopt hook
A local attacker with low privileges can trigger a kernel warning and potential denial of service by providing a negative option length in a cgroup getsockopt BPF hook.
- 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-2026-90157?
CVE-2026-90157 is a 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: Reject negative optlen in cgroup getsockopt hook
A cgroup getsockopt BPF program can shrink ctx->optlen after the kernel getsockopt handler has run. The kernel-buffer variant, used by TCP_ZEROCOPY_RECEIVE, only rejects values larger than the original length.
If BPF writes a negative optlen, that value is accepted and propagated back to the TCP getsockopt code. It can then be passed to copy_to_sockptr() as a size_t and trigger the hardened usercopy bytes > INT_MAX warning.
Reject negative ctx.optlen in __cgroup_bpf_run_filter_getsockopt_kern(), matching the lower-bound validation already present in the sockptr-based getsockopt hook.
Which versions are affected by CVE-2026-90157?
How do I fix CVE-2026-90157?
Apply the vendor's patch.
Is CVE-2026-90157 being exploited?
There is no known exploitation of CVE-2026-90157 in the wild and no public exploit code.
Sources
Also known as AZL-102590, BELL-CVE-2026-90157, DEBIAN-CVE-2026-90157, GHSA-v6r2-3cg3-jrp9, UBUNTU-CVE-2026-90157.