medium 5.5

CVE-2025-22003 json

can: ucan: fix out of bound read in strscpy() source

published 2025-04-03 19 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-9600

cvss: 5.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits: 0; none known

In the Linux kernel, the following vulnerability has been resolved:

Commit 7fdaf8966aae ("can: ucan: use strscpy() to instead of strncpy()") unintentionally introduced a one byte out of bound read on strscpy()'s source argument (which is kind of ironic knowing that strscpy() is meant to be a more secure alternative :)).

Let's consider below buffers:

dest[len + 1]; /* will be NUL terminated */ src[len]; /* may not be NUL terminated */

When doing:

strncpy(dest, src, len); dest[len] = '\0';

strncpy() will read up to len bytes from src.

On the other hand:

strscpy(dest, src, len + 1);

will read up to len + 1 bytes from src, that is to say, an out of bound read of one byte will occur on src if it is not NUL terminated. Note that the src[len] byte is never copied, but strscpy() still needs to read it to check whether a truncation occurred or not.

This exact pattern happened in ucan.

The root cause is that the source is not NUL terminated. Instead of doing a copy in a local buffer, directly NUL terminate it as soon as usb_control_msg() returns. With this, the local firmware_str[] variable can be removed.

On top of this do a couple refactors:

- ucan_ctl_payload->raw is only used for the firmware string, so rename it to ucan_ctl_payload->fw_str and change its type from u8 to char.

- ucan_device_request_in() is only used to retrieve the firmware string, so rename it to ucan_get_fw_str() and refactor it to make it directly handle all the string termination logic.

Patch / fix

fixed in 1 distros 4 links 4

Linux Linux 6.6.85, 6.12.21, 6.13.9, 6.14

debian ubuntu suse azure linux

linux Debian 14, Debian 13 6.12.21-1

debian advisories DEBIAN-CVE-2025-22003

linux Ubuntu 24.04 LTS 6.8.0-84.84
linux-aws Ubuntu 24.04 LTS 6.8.0-1039.41
linux-gcp Ubuntu 24.04 LTS 6.8.0-1040.42
linux-gke Ubuntu 24.04 LTS 6.8.0-1036.40
linux-ibm Ubuntu 24.04 LTS 6.8.0-1037.37
linux-azure Ubuntu 24.04 LTS 6.8.0-1038.44
linux-gkeop Ubuntu 24.04 LTS 6.8.0-1023.25
linux-raspi Ubuntu 24.04 LTS 6.8.0-1039.43

ubuntu advisories UBUNTU-CVE-2025-22003

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
kernel-syms-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
kernel-source-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
kernel-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.39.1
kernel-syms-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.39.1
kernel-rt_debug Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.39.1
kernel-source-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.39.1
kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1

suse advisories SUSE-SU-2025:01967-1 SUSE-SU-2025:01964-1 SUSE-SU-2025:01951-1 SUSE-SU-2025:01919-1 SUSE-SU-2025:01707-1 SUSE-SU-2025:01614-1

kernel Azure Linux 3.0 6.6.85.1-2

azure linux advisories AZL-59826

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-22003 updated 2026-11-05 cvss 5.5

kernel: can: ucan: fix out of bound read in strscpy() source

Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 13 mo ago (2025-10-01)

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

Linux Linux

Classification

Weakness

CWE-125 Out-of-bounds Read

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2025-22003
NVD CVE-2025-22003

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary