CVE-2023-53727

CPU stalls via uninterrupted FQ-PIE flow scan

Published Oct 22, 2025 · Updated Oct 22, 2025

Denial of service in the Linux kernel's FQ-PIE scheduler from 5.6 allows attackers to stall CPUs by creating many traffic flows. The fq_pie_timer() callback scans as many as 65,536 flow entries without yielding, monopolizing a CPU and blocking qdisc fast paths. Triggering the condition requires an FQ-PIE queue with a high flow count; the demonstrated result is an RCU stall and delayed packet scheduling.

CVSS severity6.8
Medium
EPSS probability0.19%
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's FQ-PIE scheduler from 5.6 allows attackers to stall CPUs by creating many traffic flows. The fq_pie_timer() callback scans as many as 65,536 flow entries without yielding, monopolizing a CPU and blocking qdisc fast paths. Triggering the condition requires an FQ-PIE queue with a high flow count; the demonstrated result is an RCU stall and delayed packet scheduling.

The record

CVE
CVE-2023-53727
Published
Oct 22, 2025
Updated
Oct 22, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 22, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 22, 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=5.6
  2. Affected versionversion=ec97ecf1ebe485a17cd8395a5f35e6b80b57665a <8c21ab1bae945686c602c5bfa4e3f3352c2452c5
  3. Affected versionversion=ec97ecf1ebe485a17cd8395a5f35e6b80b57665a <94d527c3759d76c29220758362f622954612bea7
  4. Affected versionversion=ec97ecf1ebe485a17cd8395a5f35e6b80b57665a <973a4c302d7f3804098ff9824d9f56926901f293
  5. Affected versionversion=ec97ecf1ebe485a17cd8395a5f35e6b80b57665a <e093000e7d13569c9cb07d7500acd5142c3c43cb
  6. Affected versionversion=ec97ecf1ebe485a17cd8395a5f35e6b80b57665a <f39b49077abec4c9c3a4c2966532004851c51006

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.6; version=ec97ecf1ebe485a17cd8395a5f35e6b80b57665a <8c21ab1bae945686c602c5bfa4e3f3352c2452c5; version=ec97ecf1ebe485a17cd8395a5f35e6b80b57665a <94d527c3759d76c29220758362f622954612bea7; version=ec97ecf1ebe485a17cd8395a5f35e6b80b57665a <973a4c302d7f3804098ff9824d9f56926901f293; version=ec97ecf1ebe485a17cd8395a5f35e6b80b57665a <e093000e7d13569c9cb07d7500acd5142c3c43cb; version=ec97ecf1ebe485a17cd8395a5f35e6b80b57665a <f39b49077abec4c9c3a4c2966532004851c51006

Published CVSS scores

6.8SUSECVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5SUSECVSS: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

T1499.004Application 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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