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Fencer Vulns
medium 5.5

CVE-2025-21689 json

USB: serial: quatech2: fix null-ptr-deref in qt2_process_read_urb()

published 2025-02-10 20 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-2638

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 13%
public exploits
0
none known

Summary

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

USB: serial: quatech2: fix null-ptr-deref in qt2_process_read_urb()

This patch addresses a null-ptr-deref in qt2_process_read_urb() due to an incorrect bounds check in the following:

if (newport > serial->num_ports) { dev_err(&port->dev, "%s - port change to invalid port: %i\n", __func__, newport); break; }

The condition doesn't account for the valid range of the serial->port buffer, which is from 0 to serial->num_ports - 1. When newport is equal to serial->num_ports, the assignment of "port" in the following code is out-of-bounds and NULL:

serial_priv->current_port = newport; port = serial->port[serial_priv->current_port];

The fix checks if newport is greater than or equal to serial->num_ports indicating it is out-of-bounds.

Patch / fix

  • Linux Linux 5.4.290, 5.10.234, 5.15.178, 6.1.128, 6.6.75, 6.12.12, 6.13.1, 6.14
  • linux Debian 12 6.1.128-1
  • linux Debian 14, Debian 13 6.12.12-1

debian advisories DEBIAN-CVE-2025-21689

  • linux Ubuntu 20.04 LTS 5.4.0-211.231
  • linux Ubuntu 22.04 LTS 5.15.0-135.146
  • linux Ubuntu 24.04 LTS 6.8.0-62.65
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1142.152
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1080.87
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1030.32
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1145.154
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1079.88

ubuntu advisories UBUNTU-CVE-2025-21689

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 RHEL 9 5.14.0-570.12.1.el9_6
  • rv RHEL 9 5.14.0-570.12.1.el9_6
  • perf RHEL 9 5.14.0-570.12.1.el9_6
  • rtla RHEL 9 5.14.0-570.12.1.el9_6
  • libperf RHEL 9 5.14.0-570.12.1.el9_6
  • kernel-rt RHEL 9 5.14.0-570.12.1.el9_6
  • kernel-64k RHEL 9 5.14.0-570.12.1.el9_6
  • kernel-core RHEL 9 5.14.0-570.12.1.el9_6

red hat advisories RHSA-2025:6966

  • kernel-source Linux Micro 6.1, Linux Micro 6.0 6.4.0-28.1
  • kernel-default Linux Micro 6.1, Linux Micro 6.0 6.4.0-28.1
  • kernel-kvmsmall Linux Micro 6.1, Linux Micro 6.0 6.4.0-28.1
  • kernel-default-base Linux Micro 6.1, Linux Micro 6.0 6.4.0-28.1.21.6
  • kernel-livepatch-MICRO-6-0_Update_6 Linux Micro 6.1, Linux Micro 6.0 1-3.1
  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-28.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-28.1
  • kernel-livepatch-MICRO-6-0-RT_Update_6 Linux Micro 6.1, Linux Micro 6.0 1-3.1

suse advisories SUSE-SU-2025:20192-1SUSE-SU-2025:20270-1SUSE-SU-2025:20190-1SUSE-SU-2025:20260-1SUSE-SU-2025:0955-1SUSE-SU-2025:0856-1

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-2025-21689 updated cvss 5.5

kernel: USB: serial: quatech2: fix null-ptr-deref in qt2_process_read_urb()

  • 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
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-570.12.1.el9_6, perf 5.14.0-570.12.1.el9_6, rtla 5.14.0-570.12.1.el9_6, python3-perf 5.14.0-570.12.1.el9_6, kernel-devel-matched 5.14.0-570.12.1.el9_6, kernel-64k-devel-matched 5.14.0-570.12.1.el9_6, +7 more Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-570.12.1.el9_6, kernel-64k 5.14.0-570.12.1.el9_6, kernel-core 5.14.0-570.12.1.el9_6, kernel-tools 5.14.0-570.12.1.el9_6, kernel-modules 5.14.0-570.12.1.el9_6, kernel-64k-core 5.14.0-570.12.1.el9_6, +27 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-570.12.1.el9_6, kernel-debuginfo-common-s390x 5.14.0-570.12.1.el9_6, kernel-debuginfo-common-x86_64 5.14.0-570.12.1.el9_6, kernel-debuginfo-common-aarch64 5.14.0-570.12.1.el9_6, kernel-debuginfo-common-ppc64le 5.14.0-570.12.1.el9_6 Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-570.12.1.el9_6, kernel-rt-64k 5.14.0-570.12.1.el9_6, kernel-rt-core 5.14.0-570.12.1.el9_6, kernel-rt-modules 5.14.0-570.12.1.el9_6, kernel-rt-64k-core 5.14.0-570.12.1.el9_6, kernel-rt-debug-core 5.14.0-570.12.1.el9_6, +14 more Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-570.12.1.el9_6, kernel-rt-kvm 5.14.0-570.12.1.el9_6, kernel-rt-core 5.14.0-570.12.1.el9_6, kernel-rt-modules 5.14.0-570.12.1.el9_6, kernel-rt-debug-kvm 5.14.0-570.12.1.el9_6, kernel-rt-debug-core 5.14.0-570.12.1.el9_6, +6 more
    fixed: vendor fix RHSA-2025:6966
  • 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 ICSA-25-226-07 updated cvss 5.5

Siemens Third-Party Components in SINEC OS

  • Siemens RUGGEDCOM RST2428P (6GK6242-6PA00) < 3.2
    affected: fixed in V3.2 support.industry.siemens.com
  • Siemens SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family < 3.2
    affected: fixed in V3.2
  • Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 family < 3.2
    affected: fixed in V3.2 support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
13 mo ago

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 13% 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
Technology feeds

References

Sources

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.