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CVE-2026-74431
rxrpc: Fix potential infinite loop 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-2026-74431 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 the wait in rxrpc_recvmsg() also take check the oob queue.
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
- 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
- 0.61%, higher than 48.1% 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 | 0fc5b37faec2 |
| 6.16 | 7.1.5 | da371b003a4a |
| 6.16 | 7.2 | 67a0332f442e |
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 in net/rxrpc/io_thread.c through rxrpc_input_conn_packet() into recvmsg_oobq; a malicious or compromised AFS/YFS fileserver can deliver the trigger over the network without local access.
- AC:LAttack complexity, low
- Once a victim RxGK client with RXRPC_MANAGE_RESPONSE has an established connection, a remote peer can send a valid CHALLENGE at any time and reliably strand a blocking recvmsg() in the defective wait path whenever recvmsg_q is empty but recvmsg_oobq is not.
- PR:NPrivileges required, none
- Exploitation requires only the ability to act as the remote RxRPC server peer on an existing client connection; the attacker needs no local account, capabilities, or authentication on the victim host.
- UI:NUser interaction, none
- The hang is triggered during normal blocking recvmsg() operation while waiting for call data; no additional victim action beyond routine client connectivity is required at exploitation time.
- S:UScope, unchanged
- Impact is confined to the kernel thread executing recvmsg() on the affected AF_RXRPC socket within the same security authority; there is no cross-boundary escape to other VMs, containers, or privilege domains.
- C:NConfidentiality impact, none
- This is a control-flow logic error in the recvmsg() wait loop with no out-of-bounds access, use-after-free, or information disclosure; no memory is read or leaked to the attacker.
- I:NIntegrity impact, none
- The bug causes an infinite busy-loop in recvmsg() without modifying kernel or user data, corrupting memory, or enabling arbitrary writes or code execution.
- A:HAvailability impact, high
- When recvmsg_q is empty but recvmsg_oobq holds a CHALLENGE, the pre-fix code re-enters try_again without sleeping or dequeuing OOB data, causing an infinite kernel loop that hangs the calling thread and can saturate a CPU core.