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CVE-2026-53046

ksmbd: fix use-after-free from async crypto on Qualcomm crypto engine

9.8 EPSS 0.7% AV:N

Published 2026-06-24 (4 months ago) by the Linux kernel CNA. Subsystem fs/smb. Debian urgency: not yet assigned.

What to do, per Debian release

Debian's own status for CVE-2026-53046 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	fixedDLA-4665-1 · 2026-07-03 · text	6.1.176-1	Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts.
Debian 13trixie	fixed	6.12.94-1	Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts.
Debian 14forky	fixed	7.0.10-1	Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts.
Debian unstablesid	fixed	7.0.10-1	Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts.

The vulnerability

What the bug is

ksmbd_crypt_message() sets a NULL completion callback on AEAD requests and does not handle the -EINPROGRESS return code from async hardware crypto engines like the Qualcomm Crypto Engine (QCE). When QCE returns -EINPROGRESS, ksmbd treats it as an error and immediately frees the request while the hardware DMA operation is still in flight. The DMA completion callback then dereferences freed memory, causing a NULL pointer crash: pc : qce_skcipher_done+0x24/0x174 lr : vchan_complete+0x230/0x27c ... el1h_64_irq+0x68/0x6c ksmbd_free_work_struct+0x20/0x118 [ksmbd] ksmbd_exit_file_cache+0x694/0xa4c [ksmbd] Use the standard crypto_wait_req() pattern with crypto_req_done() as the completion callback, matching the approach used by the SMB client in fs/smb/client/smb2ops.c. This properly handles both synchronous engines (immediate return) and async engines (-EINPROGRESS followed by callback notification).

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.

fs/smb/server/auth.c

What this is: KERNEL SMB3 SERVER (KSMBD)MAINTAINERS section matched on fs/smb/server/ · linux-cifs@vger.kernel.org · Maintained
Kernel module: ksmbd

Check it on the machine

grep -wE 'CONFIG_SMBFS|CONFIG_SMB_SERVER' /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 ksmbd

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 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_SMBFS, CONFIG_SMB_SERVER
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

Debian tracker CVE record NVD kernel CNA record

Signals

Published: 2026-06-24 (4 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: 0.72%, higher than 52.9% of all CVEssource
CISA KEV: not listedthe KEV catalogue
Debian urgency: not yet assignedsource
Subsystem: fs/smb

Upstream fixes

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

Introduced	Fixed in	Commit
5.15	5.15.209	57b47231055b
5.15	6.1.175	cc2da381875d
5.15	6.6.141	8fcefe840fa8
5.15	6.12.91	8ef183216fea
5.15	6.18.33	7164b3953cef
5.15	7.0.10	b46aa129fa28
5.15	7.1	3e298897f41c

Debian advisories

Advisory	Date	Shipped to	Debian
DLA-4671-1	2026-07-05	bullseye 6.1.176-1~deb11u1	tracker
DLA-4665-1	2026-07-03	bookworm 6.1.176-1	tracker

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 vulnerable code is in ksmbd, the in-kernel SMB server, and is reached by SMB3 encrypted requests/responses over the network transport such as TCP port 445.
AC:LAttack complexity, low: Once targeting a ksmbd server using an async crypto engine such as Qualcomm QCE, the attacker can trigger the bad -EINPROGRESS handling by sending encrypted SMB3 traffic; there is no attacker-uncontrolled race to win.
PR:NPrivileges required, none: The path requires a valid SMB3 session, but ksmbd supports guest/anonymous sessions that still negotiate encryption keys, making no prior privileges or credentials necessary in a reasonable guest-enabled deployment.
UI:NUser interaction, none: No victim user action is required; the attacker sends SMB traffic directly to the server.
S:UScope, unchanged: The vulnerability corrupts kernel memory within the same host security authority and does not cross a separate boundary such as guest-to-host virtualization.
C:HConfidentiality impact, high: This is a kernel heap use-after-free of an AEAD request and driver-private context, which can plausibly be shaped into memory disclosure primitives beyond the observed crash.
I:HIntegrity impact, high: The freed request is dereferenced by async crypto completion and contains pointers/callback-related state, so the UAF is defensibly treated as exploitable kernel memory corruption with potential code execution or arbitrary modification.
A:HAvailability impact, high: The reported failure is a kernel crash during async crypto completion, and repeated network-triggered UAFs can deny service to the ksmbd host.