CVE-2025-21689

System crash via invalid USB port index

Published Feb 10, 2025 · Updated May 11, 2026

NULL pointer dereference in the Linux kernel quatech2 USB serial driver allows local users to crash the system with crafted device data. qt2_process_read_urb() accepts a new port index equal to serial->num_ports, reads past the serial->port array, and assigns NULL to port. Reaching the fault requires local access and quatech2 processing of the invalid port-change value; dereferencing the resulting NULL pointer interrupts the host.

CVSS severity5.5
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux kernel quatech2 USB serial driver allows local users to crash the system with crafted device data. qt2_process_read_urb() accepts a new port index equal to serial->num_ports, reads past the serial->port array, and assigns NULL to port. Reaching the fault requires local access and quatech2 processing of the invalid port-change value; dereferencing the resulting NULL pointer interrupts the host.

The record

CVE
CVE-2025-21689
Published
Feb 10, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 10, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.5
  2. Affected versionversion=f7a33e608d9ae022b7f49307921627e34e9484ed <4b9b41fabcd38990f69ef0cee9c631d954a2b530
  3. Affected versionversion=f7a33e608d9ae022b7f49307921627e34e9484ed <575a5adf48b06a2980c9eeffedf699ed5534fade
  4. Affected versionversion=f7a33e608d9ae022b7f49307921627e34e9484ed <6068dcff7f19e9fa6fa23ee03453ad6a40fa4efe
  5. Affected versionversion=f7a33e608d9ae022b7f49307921627e34e9484ed <6377838560c03b36e1153a42ef727533def9b68f
  6. Affected versionversion=f7a33e608d9ae022b7f49307921627e34e9484ed <8542b33622571f54dfc2a267fce378b6e3840b8b
  7. Affected versionversion=f7a33e608d9ae022b7f49307921627e34e9484ed <94770cf7c5124f0268d481886829dc2beecc4507
  8. Affected versionversion=f7a33e608d9ae022b7f49307921627e34e9484ed <f371471708c7d997f763b0e70565026eb67cc470
  9. Affected versionversion=f7a33e608d9ae022b7f49307921627e34e9484ed <fa4c7472469d97c4707698b4c0e098f8cfc2bf22

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.5; version=f7a33e608d9ae022b7f49307921627e34e9484ed <4b9b41fabcd38990f69ef0cee9c631d954a2b530; version=f7a33e608d9ae022b7f49307921627e34e9484ed <575a5adf48b06a2980c9eeffedf699ed5534fade; version=f7a33e608d9ae022b7f49307921627e34e9484ed <6068dcff7f19e9fa6fa23ee03453ad6a40fa4efe; version=f7a33e608d9ae022b7f49307921627e34e9484ed <6377838560c03b36e1153a42ef727533def9b68f; version=f7a33e608d9ae022b7f49307921627e34e9484ed <8542b33622571f54dfc2a267fce378b6e3840b8b; version=f7a33e608d9ae022b7f49307921627e34e9484ed <94770cf7c5124f0268d481886829dc2beecc4507; version=f7a33e608d9ae022b7f49307921627e34e9484ed <f371471708c7d997f763b0e70565026eb67cc470; version=f7a33e608d9ae022b7f49307921627e34e9484ed <fa4c7472469d97c4707698b4c0e098f8cfc2bf22

Published CVSS scores

5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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