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NVD / CVE Program· CNA Linux

CVE-2025-37932: sch_htb: make htb_qlen_notify() idempotent

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: 0.23% (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 0a188c0e197383683fd093ab1ea6ce9a5869a6ea, 32ae12ce6a9f6bace186ca7335220ff59b6cc3cd, 5ba8b837b522d7051ef81bacf3d95383ff8edce5; azl3 kernel 6.6.85.1-4 on Azure Linux 3.0 6.6.92.2-1; azl3 kernel 6.6.92.2-1 on Azure Linux 3.0 6.6.92.2-1.

Low priority for now. Upgrade to Linux Linux 0a188c0e197383683fd093ab1ea6ce9a5869a6ea, 32ae12ce6a9f6bace186ca7335220ff59b6cc3cd, 5ba8b837b522d7051ef81bacf3d95383ff8edce5; azl3 kernel 6.6.85.1-4 on Azure Linux 3.0 6.6.92.2-1; azl3 kernel 6.6.92.2-1 on Azure Linux 3.0 6.6.92.2-1 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: sch_htb: make htb_qlen_notify() idempotent htb_qlen_notify() always deactivates the HTB class and in fact could trigger a warning if it is already deactivated. Therefore, it is not idempotent and not friendly to its callers, like fq_codel_dequeue(). Let's make it idempotent to ease qdisc_tree_reduce_backlog() callers' life.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 20, 2025
Updated
Nov 5, 2026
EPSS
0.2% · 14th percentile
CWE
—

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.

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When you'll hear from us

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  • 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
debiandebian linux

Affected versions

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

  • debian debian linux11.0
  • linux linux kernel5.5 and later · before 5.10.241
  • linux linux kernel5.11 and later · before 5.15.190
  • linux linux kernel5.16 and later · before 6.1.138
  • linux linux kernelbefore 5.4.294
  • linux linux kernel6.7 and later · before 6.12.28
  • linux linux kernel6.13 and later · before 6.14.6
  • linux linux kernel6.2 and later · before 6.6.90
  • linux linux kernel6.15

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

    • 4.14affected
    • 959466588aa7f84ccf79ae36a1d89542eaf9aaec and later · before e6b45f4de763b00dc1c55e685e2dd1aaf525d3c1affected · git
    • 959466588aa7f84ccf79ae36a1d89542eaf9aaec and later · before 32ae12ce6a9f6bace186ca7335220ff59b6cc3cdaffected · git
    • 959466588aa7f84ccf79ae36a1d89542eaf9aaec and later · before 967955c9e57f8eebfccc298037d4aaf3d42bc1c9affected · git
    • 959466588aa7f84ccf79ae36a1d89542eaf9aaec and later · before 73cf6af13153d62f9b76eff422eea79dbc70f15eaffected · git
    • 959466588aa7f84ccf79ae36a1d89542eaf9aaec and later · before bbbf5e0f87078b715e7a665d662a2c0e77f044aeaffected · git
    • 959466588aa7f84ccf79ae36a1d89542eaf9aaec and later · before 0a188c0e197383683fd093ab1ea6ce9a5869a6eaaffected · git
    • 959466588aa7f84ccf79ae36a1d89542eaf9aaec and later · before a61f1b5921761fbaf166231418bc1db301e5bf59affected · git
    • 959466588aa7f84ccf79ae36a1d89542eaf9aaec and later · before 5ba8b837b522d7051ef81bacf3d95383ff8edce5affected · git
    • before 4.14not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.140-16.1.140-1
Debian:13linuxbefore 6.12.29-16.12.29-1

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-2025-37924May 20, 2025 · ksmbd: fix use-after-free in kerberos authentication
    38Monitor
  • ← EarlierCVE-2025-37928May 20, 2025 · dm-bufio: don't schedule in atomic context
    31Monitor
  • Later →CVE-2025-37933May 20, 2025 · octeon_ep: Fix host hang issue during device reboot
    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 Linux0a188c0e197383683fd093ab1ea6ce9a5869a6eaVendor (CNA)
Linux Linux32ae12ce6a9f6bace186ca7335220ff59b6cc3cdVendor (CNA)
Linux Linux5ba8b837b522d7051ef81bacf3d95383ff8edce5Vendor (CNA)
Linux Linux73cf6af13153d62f9b76eff422eea79dbc70f15eVendor (CNA)
Linux Linux967955c9e57f8eebfccc298037d4aaf3d42bc1c9Vendor (CNA)
Linux Linuxa61f1b5921761fbaf166231418bc1db301e5bf59Vendor (CNA)
Linux Linuxbbbf5e0f87078b715e7a665d662a2c0e77f044aeVendor (CNA)
Linux Linuxe6b45f4de763b00dc1c55e685e2dd1aaf525d3c1Vendor (CNA)
azl3 kernel 6.6.85.1-4 on Azure Linux 3.06.6.92.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kernel 6.6.92.2-1 on Azure Linux 3.06.6.92.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.05.15.200.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.140-1 · 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)

—

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. SSVC exploitation— → none
  2. 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