CVE-2026-72217 SUNRPC: Bound-check xdr_buf_to_bvec() stores before writing
An out-of-bounds write in the Linux kernel SUNRPC module allows attackers to corrupt memory, potentially leading to code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72217?
CVE-2026-72217 is a critical memory corruption vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
SUNRPC: Bound-check xdr_buf_to_bvec() stores before writing
xdr_buf_to_bvec() writes a bio_vec into the caller's array before testing whether that slot is in range, and the head branch performs the store with no check at all. When the caller's budget is exactly used up, the next store lands one element past the end of the array. The overflow label returns count - 1, which masks the surplus store but cannot undo it.
rq_bvec, the array passed by nfsd_vfs_write(), is allocated to exactly rq_maxpages entries with no slack. The OOB store can land in adjacent slab memory; the bv_len and bv_offset fields written there are derived from client-supplied RPC payload sizes.
Move the in-range check ahead of the store in the head, page-loop, and tail branches. With the check at the top of each sequence, count is incremented only after a successful store, so the overflow label can return count directly.
Which versions are affected by CVE-2026-72217?
How do I fix CVE-2026-72217?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-72217 being exploited?
There is no known exploitation of CVE-2026-72217 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72217, DEBIAN-CVE-2026-72217, GHSA-jffc-255g-3gq9, UBUNTU-CVE-2026-72217.