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NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.22% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 4b9b41fabcd38990f69ef0cee9c631d954a2b530, 575a5adf48b06a2980c9eeffedf699ed5534fade, 6068dcff7f19e9fa6fa23ee03453ad6a40fa4efe; azl3 kernel 6.6.64.2-9 on Azure Linux 3.0 6.6.76.1-1; cbl2 kernel 5.15.176.3-3 on CBL Mariner 2.0 5.15.180.1-1.

Low priority for now. Upgrade to Linux Linux 4b9b41fabcd38990f69ef0cee9c631d954a2b530, 575a5adf48b06a2980c9eeffedf699ed5534fade, 6068dcff7f19e9fa6fa23ee03453ad6a40fa4efe; azl3 kernel 6.6.64.2-9 on Azure Linux 3.0 6.6.76.1-1; cbl2 kernel 5.15.176.3-3 on CBL Mariner 2.0 5.15.180.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Feb 10, 2025
Updated
Jun 17, 2026
EPSS
0.2% · 13th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2025-21689

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel3.5 and later · before 5.4.290
  • linux linux kernel5.5 and later · before 5.10.234
  • linux linux kernel5.11 and later · before 5.15.178
  • linux linux kernel5.16 and later · before 6.1.128
  • linux linux kernel6.2 and later · before 6.6.75
  • linux linux kernel6.7 and later · before 6.12.12
  • linux linux kernel6.13

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 3.5affected
    • f7a33e608d9ae022b7f49307921627e34e9484ed and later · before fa4c7472469d97c4707698b4c0e098f8cfc2bf22affected · git
    • f7a33e608d9ae022b7f49307921627e34e9484ed and later · before 94770cf7c5124f0268d481886829dc2beecc4507affected · git
    • f7a33e608d9ae022b7f49307921627e34e9484ed and later · before 6068dcff7f19e9fa6fa23ee03453ad6a40fa4efeaffected · git
    • f7a33e608d9ae022b7f49307921627e34e9484ed and later · before 4b9b41fabcd38990f69ef0cee9c631d954a2b530affected · git
    • f7a33e608d9ae022b7f49307921627e34e9484ed and later · before 6377838560c03b36e1153a42ef727533def9b68faffected · git
    • f7a33e608d9ae022b7f49307921627e34e9484ed and later · before f371471708c7d997f763b0e70565026eb67cc470affected · git
    • f7a33e608d9ae022b7f49307921627e34e9484ed and later · before 8542b33622571f54dfc2a267fce378b6e3840b8baffected · git
    • f7a33e608d9ae022b7f49307921627e34e9484ed and later · before 575a5adf48b06a2980c9eeffedf699ed5534fadeaffected · git
    • before 3.5not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.128-16.1.128-1
Debian:13linuxbefore 6.12.12-16.12.12-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2025-21687Feb 10, 2025 · vfio/platform: check the bounds of read/write syscalls
    31Monitor
  • ← EarlierCVE-2025-21688Feb 10, 2025 · drm/v3d: Assign job pointer to NULL before signaling the fence
    18Monitor
  • Later →CVE-2025-21690Feb 10, 2025 · scsi: storvsc: Ratelimit warning logs to prevent VM denial of service
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux4b9b41fabcd38990f69ef0cee9c631d954a2b530Vendor (CNA)
Linux Linux575a5adf48b06a2980c9eeffedf699ed5534fadeVendor (CNA)
Linux Linux6068dcff7f19e9fa6fa23ee03453ad6a40fa4efeVendor (CNA)
Linux Linux6377838560c03b36e1153a42ef727533def9b68fVendor (CNA)
Linux Linux8542b33622571f54dfc2a267fce378b6e3840b8bVendor (CNA)
Linux Linux94770cf7c5124f0268d481886829dc2beecc4507Vendor (CNA)
Linux Linuxf371471708c7d997f763b0e70565026eb67cc470Vendor (CNA)
Linux Linuxfa4c7472469d97c4707698b4c0e098f8cfc2bf22Vendor (CNA)
azl3 kernel 6.6.64.2-9 on Azure Linux 3.06.6.76.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.176.3-3 on CBL Mariner 2.05.15.180.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.128-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (9 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records