CVE-2025-37953

System crash via repeated HTB deactivation

Published May 20, 2025 · Updated May 11, 2026

NULL pointer dereference in Linux kernel HTB qdisc versions 6.1.138, 6.6.90, 6.12.28, and 6.14.6 allows local users to crash the system. During HTB dequeue, fq_codel_dequeue can reduce the backlog to zero and call htb_deactivate before htb_dequeue_tree calls it again, leaving clprio[prio]->ptr NULL for htb_next_rb_node. A local low-privileged user must reach the affected traffic-control dequeue path; the reported consequence is a kernel crash, not data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.18%
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 Linux kernel HTB qdisc versions 6.1.138, 6.6.90, 6.12.28, and 6.14.6 allows local users to crash the system. During HTB dequeue, fq_codel_dequeue can reduce the backlog to zero and call htb_deactivate before htb_dequeue_tree calls it again, leaving clprio[prio]->ptr NULL for htb_next_rb_node. A local low-privileged user must reach the affected traffic-control dequeue path; the reported consequence is a kernel crash, not data disclosure or modification.

The record

CVE
CVE-2025-37953
Published
May 20, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

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=0a188c0e197383683fd093ab1ea6ce9a5869a6ea <98cd7ed92753090a714f0802d4434314526fe61d
  2. Affected versionversion=32ae12ce6a9f6bace186ca7335220ff59b6cc3cd <a9945f7cf1709adc5d2d31cb6cfc85627ce299a8
  3. Affected versionversion=5ba8b837b522d7051ef81bacf3d95383ff8edce5 <3769478610135e82b262640252d90f6efb05be71
  4. Affected versionversion=6.1.138 <6.1.139
  5. Affected versionversion=6.12.28 <6.12.29
  6. Affected versionversion=6.14.6 <6.14.7
  7. Affected versionversion=6.6.90 <6.6.91
  8. Affected versionversion=73cf6af13153d62f9b76eff422eea79dbc70f15e <c928dd4f6bf0c25c72b11824a1e9ac9bd37296a0
  9. Affected versionversion=967955c9e57f8eebfccc298037d4aaf3d42bc1c9 <c2d25fddd867ce20a266806634eeeb5c30cb520c
  10. Affected versionversion=a61f1b5921761fbaf166231418bc1db301e5bf59 <c4792b9e38d2f61b07eac72f10909fa76130314b
  11. Affected versionversion=bbbf5e0f87078b715e7a665d662a2c0e77f044ae <31ff70ad39485698cf779f2078132d80b57f6c07
  12. Affected versionversion=e6b45f4de763b00dc1c55e685e2dd1aaf525d3c1 <99ff8a20fd61315bf9ae627440a5ff07d22ee153

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0a188c0e197383683fd093ab1ea6ce9a5869a6ea <98cd7ed92753090a714f0802d4434314526fe61d; version=32ae12ce6a9f6bace186ca7335220ff59b6cc3cd <a9945f7cf1709adc5d2d31cb6cfc85627ce299a8; version=5ba8b837b522d7051ef81bacf3d95383ff8edce5 <3769478610135e82b262640252d90f6efb05be71; version=6.1.138 <6.1.139; version=6.12.28 <6.12.29; version=6.14.6 <6.14.7; version=6.6.90 <6.6.91; version=73cf6af13153d62f9b76eff422eea79dbc70f15e <c928dd4f6bf0c25c72b11824a1e9ac9bd37296a0; version=967955c9e57f8eebfccc298037d4aaf3d42bc1c9 <c2d25fddd867ce20a266806634eeeb5c30cb520c; version=a61f1b5921761fbaf166231418bc1db301e5bf59 <c4792b9e38d2f61b07eac72f10909fa76130314b; version=bbbf5e0f87078b715e7a665d662a2c0e77f044ae <31ff70ad39485698cf779f2078132d80b57f6c07; version=e6b45f4de763b00dc1c55e685e2dd1aaf525d3c1 <99ff8a20fd61315bf9ae627440a5ff07d22ee153

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5UbuntuCVSS: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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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