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CVE-2026-74428
rxrpc: Fix double unlock in rxrpc_recvmsg()
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem net/rxrpc. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-74428 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
Fix a double unlock in rxrpc_recvmsg() when dealing with OOB messages.
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/rxrpc/recvmsg.c
- What this is
- RXRPC SOCKETS (AF_RXRPC)MAINTAINERS section matched on net/rxrpc/ · linux-afs@lists.infradead.org · Supported
- Kernel module
- rxrpc
Check it on the machine
grep -w CONFIG_AF_RXRPC /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 rxrpcPrints 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, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookworm, trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_AF_RXRPC
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
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.65%, higher than 50.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- net/rxrpc
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.16 | 6.18.40 | 8cd8cf3052ff |
| 6.16 | 7.1.5 | 1297ae6aeebc |
| 6.16 | 7.2 | a2f299b4d551 |
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
- RxRPC processes CHALLENGE packets from remote UDP peers; with RXRPC_MANAGE_RESPONSE and RxGK security, a network peer can queue OOB challenges that are consumed on the next recvmsg() during normal client authentication (e.g., AFS/YFS).
- AC:LAttack complexity, low
- An attacker who is the RxRPC peer (or a local user running a malicious server) can reliably deliver a CHALLENGE and trigger recvmsg() on demand; no rare timing, layout, or victim state outside attacker control is required.
- PR:NPrivileges required, none
- No administrative capability is needed on the victim; any remote peer in an RxRPC connection can send CHALLENGE packets, and unprivileged local users can create AF_RXRPC sockets, set MANAGE_RESPONSE, and call recvmsg() without special privileges.
- UI:NUser interaction, none
- Exploitation does not require victim interaction beyond normal automated RxRPC/AFS client operation; recvmsg() is invoked automatically when OOB challenges are queued during connection security negotiation.
- S:UScope, unchanged
- Impact is confined to kernel memory and locking on the affected host; it does not cross VM, container, or IOMMU security boundaries into a separate authority.
- C:HConfidentiality impact, high
- Double release_sock() corrupts socket lock ownership, allowing concurrent unsynchronized access to socket/call state and adjacent kernel heap objects, which can be leveraged for arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- The corrupted socket lock permits overlapping recvmsg()/sendmsg() access to connection and skb state, enabling heap corruption and control-flow hijack primitives typical of kernel locking bugs.
- A:HAvailability impact, high
- The double unlock triggers lockdep warnings and can panic/oops the kernel or hang socket I/O when concurrent threads access the same RxRPC socket after ownership is incorrectly cleared.