Look up another CVE · open CVE-2026-89535 in the interactive tracker
CVE-2026-89535
svcrdma: Reorder rpcrdma_rn_unregister before rdma_destroy_id
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem net/sunrpc. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-89535 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
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).
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/sunrpc/xprtrdma/svc_rdma_transport.c
- What this is
- KERNEL NFSD, SUNRPC, AND LOCKD SERVERSMAINTAINERS section matched on net/sunrpc/ · linux-nfs@vger.kernel.org · Supported
- Kernel module
- rpcrdma
Check it on the machine
grep -wE 'CONFIG_SUNRPC|CONFIG_SUNRPC_XPRT_RDMA' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w rpcrdmaPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sid, bookworm · linux-6.12m
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switches
- CONFIG_SUNRPC, CONFIG_SUNRPC_XPRT_RDMA
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-11 (37 days ago)source
- CVSS
- 8.1 high
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.54%, higher than 44.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- net/sunrpc
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.12 | 6.12.111 | fcd4a752ac84 |
| 6.12 | 6.18.51 | 9f2f5d099936 |
| 6.12 | 7.2.4 | cfca6eb3345b |
| 6.12 | 7.3 | 4488e9129737 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- svcrdma is nfsd's RPC-over-RDMA server transport; a remote peer over routable RoCEv2 or iWARP reaches svc_rdma_free() by disconnecting an accepted connection or by forcing the post-rpcrdma_rn_register accept-error path after CONNECT_REQUEST.
- AC:HAttack complexity, high
- The UAF exists only between rdma_destroy_id() and rpcrdma_rn_unregister(); triggering it requires a concurrent ib_unregister_device xarray walk (unbind, VF hot-unplug, or rxe/siw link delete) that a remote peer cannot initiate or reliably time.
- PR:NPrivileges required, none
- RDMA CM CONNECT_REQUEST, accept, and DISCONNECT run before RPC or NFS authentication, and the CM handshake has no credential check, so an unauthenticated peer can drive the teardown path.
- UI:NUser interaction, none
- Opening and dropping RPC-over-RDMA connections against an already-listening NFS/RDMA service is sufficient; concurrent administrative device removal is attack complexity, not victim user interaction.
- S:UScope, unchanged
- The use-after-free of the rdma_cm_id and any double-put of the svcxprt_rdma remain in the host kernel; this is not a VM, IOMMU, or sandbox escape.
- C:HConfidentiality impact, high
- A concurrent rpcrdma_remove_one() walk calls svc_rdma_xprt_done(), which reads the already-freed sc_cm_id (device name and route address); a reclaimable slab UAF is confidentiality High per kernel UAF guidance.
- I:HIntegrity impact, high
- On the accept-failure path the same callback can svc_xprt_close() a transport whose kref is already zero, calling rdma_disconnect() on the freed cm_id and dropping the kref again, yielding a double-free/UAF write primitive.
- A:HAvailability impact, high
- Dereferencing the freed rdma_cm_id or double-freeing the svcxprt_rdma causes a kernel oops or panic; any use-after-free is availability High per kernel CVSS guidance.