5.5

CVE-2025-21689: USB: serial: quatech2: fix null-ptr-deref in qt2_process_read_urb()

Modified
AliasesUBUNTU-CVE-2025-21689DEBIAN-CVE-2025-21689
Published 10-02-2025Last modified 11-05-2026

Vulnerability summary

CVE-2025-21689 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.23% chance of exploitation in the next 30 days, higher than 13.3% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.5/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.23%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 46 · Related 41
DLA-4075-1DLA-4076-1MGASA-2025-0078MGASA-2025-0079RHSA-2025:6966SUSE-SU-2025:0784-1

Timeline

  1. 10-02-2025
    PublishedVulnerability first disclosed.
  2. 11-05-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.23%

Chance of exploitation in the next 30 days

Percentile

13%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.23% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu136 products
  • linuxAll versions (No fix recorded) | < 5.4.0-211.231 | < 5.15.0-135.146 | < 6.8.0-62.65
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 5.4.0-1142.152 | < 5.15.0-1080.87 | < 6.8.0-1030.32
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ f7a33e608d9ae022b7f49307921627e34e9484ed, < fa4c7472469d97c4707698b4c0e098f8cfc2bf22 | ≥ f7a33e608d9ae022b7f49307921627e34e9484ed, < 94770cf7c5124f0268d481886829dc2beecc4507 | ≥ f7a33e608d9ae022b7f49307921627e34e9484ed, < 6068dcff7f19e9fa6fa23ee03453ad6a40fa4efe | ≥ f7a33e608d9ae022b7f49307921627e34e9484ed, < 4b9b41fabcd38990f69ef0cee9c631d954a2b530 | ≥ f7a33e608d9ae022b7f49307921627e34e9484ed, < 6377838560c03b36e1153a42ef727533def9b68f | ≥ f7a33e608d9ae022b7f49307921627e34e9484ed, < f371471708c7d997f763b0e70565026eb67cc470 | ≥ f7a33e608d9ae022b7f49307921627e34e9484ed, < 8542b33622571f54dfc2a267fce378b6e3840b8b | ≥ f7a33e608d9ae022b7f49307921627e34e9484ed, < 575a5adf48b06a2980c9eeffedf699ed5534fade | 3.5
  • linux_kernelEOL≥ 3.5, < 5.4.290 | ≥ 5.5, < 5.10.234 | ≥ 5.11, < 5.15.178 | ≥ 5.16, < 6.1.128 | ≥ 6.2, < 6.6.75 | ≥ 6.7, < 6.12.12 | 6.13 | 6.13:rc1 | 6.13:rc2 | 6.13:rc3 | 6.13:rc4 | 6.13:rc5 | 6.13:rc6 | 6.13:rc7
Debian1 product
  • linux< 6.1.128-1 | < 6.12.12-1

3 vendors · 139 products

References

46 links
Show all 46 references