CVE-2023-54269 SUNRPC: double free xprt_ctxt while still in use
A double free vulnerability in the Linux kernel SUNRPC subsystem allows attackers to cause a denial of service 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-2023-54269?
CVE-2023-54269 is a critical use after free vulnerability in Linux, published on 30 Dec 2025. 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: double free xprt_ctxt while still in use
When an RPC request is deferred, the rq_xprt_ctxt pointer is moved out of the svc_rqst into the svc_deferred_req. When the deferred request is revisited, the pointer is copied into the new svc_rqst - and also remains in the svc_deferred_req.
In the (rare?) case that the request is deferred a second time, the old svc_deferred_req is reused - it still has all the correct content. However in that case the rq_xprt_ctxt pointer is NOT cleared so that when xpo_release_xprt is called, the ctxt is freed (UDP) or possible added to a free list (RDMA). When the deferred request is revisited for a second time, it will reference this ctxt which may be invalid, and the free the object a second time which is likely to oops.
So change svc_defer() to *always* clear rq_xprt_ctxt, and assert that the value is now stored in the svc_deferred_req.
Which versions are affected by CVE-2023-54269?
How do I fix CVE-2023-54269?
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-2023-54269 being exploited?
There is no known exploitation of CVE-2023-54269 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2023-54269, DEBIAN-CVE-2023-54269, GHSA-cphq-rv4m-x79g, UBUNTU-CVE-2023-54269.