CVE-2026-89535 svcrdma: Reorder rpcrdma_rn_unregister before rdma_destroy_id
A use-after-free vulnerability in the Linux kernel's svcrdma module allows attackers to cause denial of service or potentially execute code via race conditions during device unregistration.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89535?
CVE-2026-89535 is a high-severity use after free vulnerability in Linux, published on 11 Sep 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:
svcrdma: Reorder rpcrdma_rn_unregister before rdma_destroy_id
svc_rdma_free() caches rdma->sc_cm_id->device before teardown, then calls rdma_destroy_id(sc_cm_id) which frees the cm_id. rpcrdma_rn_unregister() follows, but between those two calls the transport's sc_rn entry is still installed in the device's rd_xa. A concurrent ib_unregister_device walk can dispatch svc_rdma_xprt_done() against the now-freed sc_cm_id.
Move rpcrdma_rn_unregister() before rdma_destroy_id() so the transport's notification entry is removed from the xarray before the cm_id it references is destroyed.
Also guard the sc_cm_id dereference with a NULL check: the following patches introduce paths that reach svc_rdma_free() with sc_cm_id == NULL (listener create failure, ADDR_CHANGE replacement failure).
Which versions are affected by CVE-2026-89535?
How do I fix CVE-2026-89535?
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-2026-89535 being exploited?
There is no known exploitation of CVE-2026-89535 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-89535, DEBIAN-CVE-2026-89535, GHSA-xqw2-jp99-qfhh, UBUNTU-CVE-2026-89535.