CVE-2026-72220
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk10th percentile - higher than 10% of all known CVEs
Summary
In the Linux kernel's sunrpc subsystem, svc_release_rqst() executes the callback in rqstp->rq_procinfo->pc_release. If a worker thread hits an early error path before a valid rq_procinfo is installed, a stale release hook can be re-triggered against reused state from the previous RPC, leading to double-free or use-after-free. The fix hardens the rq_procinfo lifecycle by clearing it after pc_release, at request entry in svc_process(), and in svc_process_bc().
Risk Assessment
The vulnerability can lead to system crashes, memory corruption, or potentially remote code execution, posing a serious threat to security and service availability.
Recommendation
Immediately update the Linux kernel to a version containing the fix for CVE-2026-72220 to eliminate the risk of double-free or use-after-free.
Original NVD description (English source)
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.