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CVE-2026-72465
xprtrdma: Sanitize the reply credit grant after parsing
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem net/sunrpc. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-72465 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 | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The out_norqst exit in rpcrdma_reply_handler() branches away before the credit clamp, so a reply that matches no pending request reaches out_post carrying the raw credit value parsed from the wire. rpcrdma_post_recvs() does not bound its @needed argument: the refill loop allocates and chains Receive WRs until the count is satisfied or allocation fails. A peer that sends a well-formed reply carrying an unknown XID and an inflated credit grant therefore drives rep allocation and Receive posting past re_max_requests on every such reply. Move the clamp to immediately after the credit field is parsed, ahead of the first branch that can reach out_post, so every later consumer sees a sanitized value. The cwnd update stays on the matched-request path.
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/rpc_rdma.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
- 2026-08-15 (2 months ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.68%, higher than 51.6% 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 |
|---|---|---|
| 6.1.178 | 6.1.178 | 7cf332b3d82d |
| 6.6.145 | 6.6.145 | 416342421401 |
| 6.12.97 | 6.12.97 | 8be1bb378def |
| 6.18.40 | 6.18.40 | 469b22376ee7 |
| 7.1 | 7.1.5 | 33db78b1b24f |
| 7.1 | 7.2 | c3a628aab2dc |
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
- The flaw is in the NFS-over-RDMA client receive path: rpcrdma_wc_receive() delivers remote RDMA reply completions to rpcrdma_reply_handler(), so a malicious or compromised NFS/RDMA server can send crafted replies over InfiniBand/RoCE/iWARP without local access.
- AC:LAttack complexity, low
- On an established RPC/RDMA session the peer fully controls inbound replies and can reliably send well-formed headers with an unknown XID and an inflated credit grant on every message, deterministically reaching out_norqst and out_post without races or special victim state.
- PR:NPrivileges required, none
- Exploitation requires only network reachability as the connected RDMA/RPC peer; the attacker does not need local accounts, mount privileges, or namespaced capabilities on the victim NFS client to deliver malicious reply traffic.
- UI:NUser interaction, none
- Once an NFS-over-RDMA mount and transport session exist, the attacker can flood spurious replies during normal client-server communication without any additional victim or administrator action at exploit time.
- S:UScope, unchanged
- Impact is confined to excessive kernel memory allocation and denial of service within the NFS client's SUNRPC/xprtrdma transport; it does not cross VM, container, or IOMMU security boundaries.
- C:NConfidentiality impact, none
- The bug is unbounded receive-buffer allocation driven by an unsanitized wire credit field, not an out-of-bounds read, use-after-free, or other memory disclosure primitive that exposes kernel data to the attacker.
- I:NIntegrity impact, none
- Inflated credits only cause rpcrdma_post_recvs() to allocate and post extra rpcrdma_rep objects; there is no demonstrated memory corruption, arbitrary write, or control-flow hijack primitive.
- A:HAvailability impact, high
- Each spurious reply can drive rpcrdma_rep_create() far past re_max_requests until allocation fails, enabling repeated remote kernel memory exhaustion, OOM conditions, and loss of NFS-over-RDMA service on the client.