CVE-2023-53624

CPU soft lockup via overflowing FQ credit

Published Oct 7, 2025 · Updated Oct 7, 2025

Integer overflow in the Linux kernel's FQ scheduler allows local users to cause a CPU soft lockup through an oversized initial quantum. sch_fq stores the unsigned initial_quantum value in a signed per-flow credit field without first limiting it to INT_MAX, turning larger values into a large negative credit. Reachability requires local privileges to configure the FQ qdisc; the resulting scheduler stall can interrupt service but is not an infinite loop.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in the Linux kernel's FQ scheduler allows local users to cause a CPU soft lockup through an oversized initial quantum. sch_fq stores the unsigned initial_quantum value in a signed per-flow credit field without first limiting it to INT_MAX, turning larger values into a large negative credit. Reachability requires local privileges to configure the FQ qdisc; the resulting scheduler stall can interrupt service but is not an infinite loop.

The record

CVE
CVE-2023-53624
Published
Oct 7, 2025
Updated
Oct 7, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-190, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 7, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 7, 2025Record 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=3.12
  2. Affected versionversion=afe4fd062416b158a8a8538b23adc1930a9b88dc <2322462d6f9ad4874f4e3c63df3b5cc00cb1acbd
  3. Affected versionversion=afe4fd062416b158a8a8538b23adc1930a9b88dc <4b8a05e3801661a0438fcd0cdef181030d966a5a
  4. Affected versionversion=afe4fd062416b158a8a8538b23adc1930a9b88dc <4fbefeab88c6e79753a25099d455d3d59d2946b4
  5. Affected versionversion=afe4fd062416b158a8a8538b23adc1930a9b88dc <7041101ff6c3073fd8f2e99920f535b111c929cb
  6. Affected versionversion=afe4fd062416b158a8a8538b23adc1930a9b88dc <85f24cb2f10b2b0f2882e5786a09b4790bb3a0ad
  7. Affected versionversion=afe4fd062416b158a8a8538b23adc1930a9b88dc <d0b43125ec892aeb1b03e5df5aab595097da225a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.12; version=afe4fd062416b158a8a8538b23adc1930a9b88dc <2322462d6f9ad4874f4e3c63df3b5cc00cb1acbd; version=afe4fd062416b158a8a8538b23adc1930a9b88dc <4b8a05e3801661a0438fcd0cdef181030d966a5a; version=afe4fd062416b158a8a8538b23adc1930a9b88dc <4fbefeab88c6e79753a25099d455d3d59d2946b4; version=afe4fd062416b158a8a8538b23adc1930a9b88dc <7041101ff6c3073fd8f2e99920f535b111c929cb; version=afe4fd062416b158a8a8538b23adc1930a9b88dc <85f24cb2f10b2b0f2882e5786a09b4790bb3a0ad; version=afe4fd062416b158a8a8538b23adc1930a9b88dc <d0b43125ec892aeb1b03e5df5aab595097da225a

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1499Endpoint Denial of Service

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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