CVE-2026-74590 fsverity: Fix bpf_get_fsverity_digest() dynptr assumptions
A race condition in the Linux kernel's fsverity BPF helper can cause a crash if digest size is concurrently modified, leading to denial of service.
- 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-2026-74590?
CVE-2026-74590 is a high-severity vulnerability in Linux, published on 22 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:
fsverity: Fix bpf_get_fsverity_digest() dynptr assumptions
The BPF verifier and the dynptr abstraction ensure that the memory space referenced by a dynptr remains valid. They do not, however, provide any guarantee that the contents of the memory are stable. kfuncs are expected to remain memory-safe even if concurrent modifications occur.
bpf_get_fsverity_digest() didn't follow that: it could crash if arg->digest_size was concurrently modified.
Fix that by using the known-good value hash_alg->digest_size instead.
Also widen 'dynptr_sz' and 'out_digest_sz' to u64 to match the return type of __bpf_dynptr_size(). It doesn't appear that it can actually be more than INT_MAX currently (since __bpf_dynptr_data_rw() excludes file-based pointers), but the correct type might as well be used.
Which versions are affected by CVE-2026-74590?
How do I fix CVE-2026-74590?
Apply the vendor's patch.
Is CVE-2026-74590 being exploited?
There is no known exploitation of CVE-2026-74590 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74590, DEBIAN-CVE-2026-74590, GHSA-pxx7-9r2r-m5m2, UBUNTU-CVE-2026-74590.