CVE-2025-38637

Local service interruption via SKBPRIO queue assertion

Published Apr 18, 2025 · Updated May 11, 2026

A queue assertion flaw in affected Linux kernel versions allows local users to interrupt service through crafted traffic-control settings. A token-starved TBF peek leaves the parent and child queue-length counters inconsistent, so a later high-priority packet triggers SKBPRIO's overly strict assertion. Exploitation requires SKBPRIO beneath TBF with specific parameters; the public record does not identify whether interruption produces a hang, crash, or reboot.

CVSS severity5.5
Medium
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A queue assertion flaw in affected Linux kernel versions allows local users to interrupt service through crafted traffic-control settings. A token-starved TBF peek leaves the parent and child queue-length counters inconsistent, so a later high-priority packet triggers SKBPRIO's overly strict assertion. Exploitation requires SKBPRIO beneath TBF with specific parameters; the public record does not identify whether interruption produces a hang, crash, or reboot.

The record

CVE
CVE-2025-38637
Published
Apr 18, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 18, 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=4.19
  2. Affected versionversion=aea5f654e6b78a0c976f7a25950155932c77a53f <034b293bf17c124fec0f0e663f81203b00aa7a50
  3. Affected versionversion=aea5f654e6b78a0c976f7a25950155932c77a53f <1284733bab736e598341f1d3f3b94e2a322864a8
  4. Affected versionversion=aea5f654e6b78a0c976f7a25950155932c77a53f <1dcc144c322a8d526b791135604c0663f1af9d85
  5. Affected versionversion=aea5f654e6b78a0c976f7a25950155932c77a53f <2286770b07cb5268c03d11274b8efd43dff0d380
  6. Affected versionversion=aea5f654e6b78a0c976f7a25950155932c77a53f <2f35b7673a3aa3d09b3eb05811669622ebaa98ca
  7. Affected versionversion=aea5f654e6b78a0c976f7a25950155932c77a53f <32ee79682315e6d3c99947b3f38b078a09a66919
  8. Affected versionversion=aea5f654e6b78a0c976f7a25950155932c77a53f <7abc8318ce0712182bf0783dcfdd9a6a8331160e
  9. Affected versionversion=aea5f654e6b78a0c976f7a25950155932c77a53f <864ca690ff135078d374bd565b9872f161c614bc
  10. Affected versionversion=aea5f654e6b78a0c976f7a25950155932c77a53f <ce8fe975fd99b49c29c42e50f2441ba53112b2e8

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.19; version=aea5f654e6b78a0c976f7a25950155932c77a53f <034b293bf17c124fec0f0e663f81203b00aa7a50; version=aea5f654e6b78a0c976f7a25950155932c77a53f <1284733bab736e598341f1d3f3b94e2a322864a8; version=aea5f654e6b78a0c976f7a25950155932c77a53f <1dcc144c322a8d526b791135604c0663f1af9d85; version=aea5f654e6b78a0c976f7a25950155932c77a53f <2286770b07cb5268c03d11274b8efd43dff0d380; version=aea5f654e6b78a0c976f7a25950155932c77a53f <2f35b7673a3aa3d09b3eb05811669622ebaa98ca; version=aea5f654e6b78a0c976f7a25950155932c77a53f <32ee79682315e6d3c99947b3f38b078a09a66919; version=aea5f654e6b78a0c976f7a25950155932c77a53f <7abc8318ce0712182bf0783dcfdd9a6a8331160e; version=aea5f654e6b78a0c976f7a25950155932c77a53f <864ca690ff135078d374bd565b9872f161c614bc; version=aea5f654e6b78a0c976f7a25950155932c77a53f <ce8fe975fd99b49c29c42e50f2441ba53112b2e8

Published CVSS scores

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

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

T1499Endpoint Denial of Service

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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