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CVE-2026-89534
svcrdma: Clear sc_cm_id when ADDR_CHANGE replacement fails
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-2026-89534 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 | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| 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. |
The vulnerability
What the bug is
When svc_rdma_listen_handler() handles RDMA_CM_EVENT_ADDR_CHANGE, it creates a replacement listener cm_id and returns 1, telling the CM core to destroy the old one. If the replacement allocation fails, sc_cm_id still points at the old cm_id that the CM core is about to destroy. Any subsequent dereference of sc_cm_id -- such as svc_rdma_detach()'s rdma_disconnect() call -- is a use-after-free. NULL sc_cm_id on the failure path and guard svc_rdma_detach()'s rdma_disconnect() call against NULL so that the listener can be torn down safely when the server shuts down.
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, sidm
- 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
- 8.8 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.36%, higher than 28.8% 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 |
|---|---|---|
| 6.11 | 6.18.57 | 65f0f82f2033 |
| 6.11 | 7.2.4 | 673e358ab7c1 |
| 6.11 | 7.3 | 01500306e1d5 |
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:AAttack vector, adjacent network
- svcrdma is the in-kernel NFS/RDMA server listen path; RDMA_CM_EVENT_ADDR_CHANGE is raised only from cma_netdev_callback on NETDEV_BONDING_FAILOVER when the bound bond MAC changes, so an attacker on the RoCE/IB storage fabric inducing active-backup failover reaches the bug, matching ADDR_CHANGE scoring for RPC-over-RDMA.
- AC:LAttack complexity, low
- svc_rdma_create_listen_id() binds the replacement while the old listen cm_id still owns the port, so rdma_bind_addr() fails deterministically with EADDRINUSE/EADDRNOTAVAIL; the handler still returns 1 and the CM core frees that id, leaving a dangling sc_cm_id the attacker can arm by inducing failover.
- PR:NPrivileges required, none
- The NFS/RDMA listener is already running as a network service; bonding failover and RDMA CM ADDR_CHANGE delivery perform no RPC, NFS export, or other authentication, so an adjacent fabric attacker needs no account or capability on the victim host.
- UI:NUser interaction, none
- Exploitation uses attacker-induced link failover plus subsequent listener teardown (nfsd restart/shutdown, the normal operational response once the listen endpoint is dead); no separate victim action such as mounting a filesystem or opening a file is required.
- S:UScope, unchanged
- The use-after-free corrupts the host kernel rdma_cm_id/rdma_id_private object used by nfsd's RDMA transport in the same kernel security authority and is not a VM, IOMMU, or sandbox escape.
- C:HConfidentiality impact, high
- After the CM core destroys the listen id, sc_cm_id is a dangling pointer to a freed rdma_cm_id with an event_handler; later rdma_disconnect()/rdma_destroy_id() in svc_rdma_detach/free is a kernel heap UAF that enables arbitrary disclosure via controlled reuse.
- I:HIntegrity impact, high
- svc_rdma_detach() calls rdma_disconnect() on the freed cm_id and svc_rdma_free() may rdma_destroy_id() it again, yielding UAF writes, double-free, and function-pointer hijack of event_handler, so integrity impact is High per UAF guidance.
- A:HAvailability impact, high
- Use-after-free of the listen rdma_cm_id during detach/free causes a kernel oops or panic even when not fully exploited, so availability impact is High.