CVE-2026-90323

What the bug is

With UBLK_F_AUTO_BUF_REG, invalid sqe->addr can fail after ublk_fill_io_cmd() has set UBLK_IO_FLAG_ACTIVE. The uring_cmd is completed while the tag stays active, which can hang teardown. Split validation from buffer apply so the check has no side effects, then take the uring_cmd and store the already-validated buffer. Apply the same order in FETCH so io->buf is not written before __ublk_fetch() state checks.

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.

drivers/block/ublk_drv.c

What this is

UBLK USERSPACE BLOCK DRIVERMAINTAINERS section matched on drivers/block/ublk_drv.c · linux-block@vger.kernel.org · Maintained

Kernel module

ublk_drv

Check it on the machine

grep -w CONFIG_BLK_DEV_UBLK /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 ublk_drv

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 does not build this code in 1 release. It does build it in 3 releases, so the answer depends on which release the machine runs.

• bookwormn
• trixie, forky, sidm

n

not enabled on any flavour - this release does not build the code

m

a loadable module on every flavour - check lsmod, can be blacklisted

Build switch

CONFIG_BLK_DEV_UBLK

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

2026-09-17 (31 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.21%, higher than 10.0% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

unimportantsource

Subsystem

drivers/block

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
6.17	6.18.57	8397942b6712
6.17	7.2.6	653d22269a8b
6.17	7.3	ca5a01eee34c