CVE-2026-89545
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
In the Linux kernel, svc_rqst_free() frees rq_argp and rq_resp synchronously while deferring the rqstp struct free via kfree_rcu(). This creates a window where RCU readers can access already freed fields, leading to a use-after-free.
Risk Assessment
This can lead to use-after-free, potentially enabling privilege escalation or kernel crash. However, it requires local access to RPC operations or invoking the relevant interface.
Recommendation
Update the Linux kernel to a version containing the fix that moves the kfree of rq_argp and rq_resp into an explicit call_rcu() callback. Check systems using NFS/SUNRPC.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: sunrpc: defer rq_argp and rq_resp free until after RCU grace period svc_rqst_free() frees rqstp->rq_argp and rqstp->rq_resp synchronously via kfree(), but defers the rqstp struct free via kfree_rcu(). After svc_exit_thread() calls list_del_rcu() and svc_rqst_free(), there is a window where RCU readers that started before list_del_rcu() can still traverse the thread list and find the rqstp. These readers (e.g. nfsd_nl_rpc_status_get_dumpit()) dereference rqstp->rq_argp, which has already been freed — a use-after-free. Fix this by moving the kfree of rq_argp and rq_resp into an explicit call_rcu() callback alongside the struct free. Resources not accessed by RCU readers (bvec, buffer pages, scratch folio, auth_data) remain synchronously freed.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

