CVE-2025-37932

Service interruption via repeated HTB class deactivation

Published May 20, 2025 · Updated May 11, 2026

Denial of service in the Linux kernel HTB scheduler allows local users to trigger a warning through queue backlog processing. In net/sched/sch_htb.c, htb_qlen_notify() unconditionally calls htb_deactivate() even when prio_activity shows that the class is already inactive. The path requires local high-privileged traffic-control access; published evidence establishes a warning and low availability impact, not a kernel crash.

CVSS severity5.5
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Linux kernel HTB scheduler allows local users to trigger a warning through queue backlog processing. In net/sched/sch_htb.c, htb_qlen_notify() unconditionally calls htb_deactivate() even when prio_activity shows that the class is already inactive. The path requires local high-privileged traffic-control access; published evidence establishes a warning and low availability impact, not a kernel crash.

The record

CVE
CVE-2025-37932
Published
May 20, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. May 20, 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=4.14
  2. Affected versionversion=959466588aa7f84ccf79ae36a1d89542eaf9aaec <0a188c0e197383683fd093ab1ea6ce9a5869a6ea
  3. Affected versionversion=959466588aa7f84ccf79ae36a1d89542eaf9aaec <32ae12ce6a9f6bace186ca7335220ff59b6cc3cd
  4. Affected versionversion=959466588aa7f84ccf79ae36a1d89542eaf9aaec <5ba8b837b522d7051ef81bacf3d95383ff8edce5
  5. Affected versionversion=959466588aa7f84ccf79ae36a1d89542eaf9aaec <73cf6af13153d62f9b76eff422eea79dbc70f15e
  6. Affected versionversion=959466588aa7f84ccf79ae36a1d89542eaf9aaec <967955c9e57f8eebfccc298037d4aaf3d42bc1c9
  7. Affected versionversion=959466588aa7f84ccf79ae36a1d89542eaf9aaec <a61f1b5921761fbaf166231418bc1db301e5bf59
  8. Affected versionversion=959466588aa7f84ccf79ae36a1d89542eaf9aaec <bbbf5e0f87078b715e7a665d662a2c0e77f044ae
  9. Affected versionversion=959466588aa7f84ccf79ae36a1d89542eaf9aaec <e6b45f4de763b00dc1c55e685e2dd1aaf525d3c1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linuxversion=4.14; version=959466588aa7f84ccf79ae36a1d89542eaf9aaec <0a188c0e197383683fd093ab1ea6ce9a5869a6ea; version=959466588aa7f84ccf79ae36a1d89542eaf9aaec <32ae12ce6a9f6bace186ca7335220ff59b6cc3cd; version=959466588aa7f84ccf79ae36a1d89542eaf9aaec <5ba8b837b522d7051ef81bacf3d95383ff8edce5; version=959466588aa7f84ccf79ae36a1d89542eaf9aaec <73cf6af13153d62f9b76eff422eea79dbc70f15e; version=959466588aa7f84ccf79ae36a1d89542eaf9aaec <967955c9e57f8eebfccc298037d4aaf3d42bc1c9; version=959466588aa7f84ccf79ae36a1d89542eaf9aaec <a61f1b5921761fbaf166231418bc1db301e5bf59; version=959466588aa7f84ccf79ae36a1d89542eaf9aaec <bbbf5e0f87078b715e7a665d662a2c0e77f044ae; version=959466588aa7f84ccf79ae36a1d89542eaf9aaec <e6b45f4de763b00dc1c55e685e2dd1aaf525d3c1

Published CVSS scores

1.9OracleCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L
7.0Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/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

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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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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