CVE-2026-72220 sunrpc: harden rq_procinfo lifecycle to prevent double-free
A double-free or use-after-free in the Linux kernel's sunrpc module allows attackers to potentially execute code or escalate privileges via crafted RPC requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72220?
CVE-2026-72220 is a critical use after free 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: harden rq_procinfo lifecycle to prevent double-free
The svc_release_rqst() function executes the callback inside rqstp->rq_procinfo->pc_release. However, if a worker thread begins processing a new request and encounters an early error path (e.g., unsupported protocol, short frame, or bad auth) before a valid rq_procinfo is installed, a stale release hook can be re-triggered against reused state from the previous RPC, resulting in a double-free or use-after-free vulnerability.
Harden the lifecycle of rq_procinfo by: 1. Ensuring svc_release_rqst() always clears rq_procinfo after the optional pc_release() call, regardless of whether the hook exists. 2. Explicitly clearing rq_procinfo at request entry in svc_process() before any early decode or drop paths. 3. Ensuring svc_process_bc() does the same at backchannel entry.
This guarantees that error flows will not encounter a non-NULL stale rq_procinfo pointer when there is nothing to release.
Which versions are affected by CVE-2026-72220?
How do I fix CVE-2026-72220?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-72220 being exploited?
There is no known exploitation of CVE-2026-72220 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72220, DEBIAN-CVE-2026-72220, GHSA-m4wq-7wv4-xpq8, UBUNTU-CVE-2026-72220.