CVE-2025-38544

What the bug is

When userspace is using AF_RXRPC to provide a server, it has to preallocate incoming calls and assign to them call IDs that will be used to thread related recvmsg() and sendmsg() together. The preallocated call IDs will automatically be attached to calls as they come in until the pool is empty. To the kernel, the call IDs are just arbitrary numbers, but userspace can use the call ID to hold a pointer to prepared structs. In any case, the user isn't permitted to create two calls with the same call ID (call IDs become available again when the call ends) and EBADSLT should result from sendmsg() if an attempt is made to preallocate a call with an in-use call ID. However, the cleanup in the error handling will trigger both assertions in rxrpc_cleanup_call() because the call isn't marked complete and isn't marked as having been released. Fix this by setting the call state in rxrpc_service_prealloc_one() and then marking it as being released before calling the cleanup function.

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/call_accept.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 rxrpc

Prints 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

2025-08-16 (14 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.15%, higher than 4.1% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

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
4.9	6.6.99	432c5363cd6f
4.9	6.12.39	5385ad53793d
4.9	6.15.7	d8ffb47a4439
4.9	6.16	69e4186773c6