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Full vulnerability report · 2024
CVE-2024-25111High confidence

SQUID-2024:1 Denial of Service in HTTP Chunked Decoding

squid-cache · squid

Official source article: GitHub GHSA-72C2-C3WM-8QXC ↗. Check the applicable product and release in the original source.

8.6HighCVSS 3.1
Recommended action
Within 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Critical, raised one band.upgradedsince 3 Nov 2025

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 65.25% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs squid-cache squid and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Distribution package intelligence

Release-specific package status

Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

5 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcesquidVendor fix publishedDebian records a fixed source-package version for this release.6.8-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourcesquidVendor fix publishedDebian records a fixed source-package version for this release.5.7-2+deb12u1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourcesquidVendor fix publishedDebian records a fixed source-package version for this release.6.8-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourcesquidVendor fix publishedDebian records a fixed source-package version for this release.6.8-1Debian Security Tracker ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivesquidVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.6.6-1ubuntu4Canonical Ubuntu Security ↗Source updated 5 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2024-25111 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitysquid: Denial of Service in HTTP Chunked Decoding
197 fixed

The vendor explicitly identifies these products or versions as containing the fix.

  • libecap-0:1.0.1-2.module+el8.1.0+4044+36416a77.src (squid:4) as a component of Red Hat Enterprise Linux AppStream AUS (v. 8.2)
  • libecap-0:1.0.1-2.module+el8.1.0+4044+36416a77.x86_64 (squid:4) as a component of Red Hat Enterprise Linux AppStream AUS (v. 8.2)
  • libecap-debuginfo-0:1.0.1-2.module+el8.1.0+4044+36416a77.x86_64 (squid:4) as a component of Red Hat Enterprise Linux AppStream AUS (v. 8.2)
  • libecap-debugsource-0:1.0.1-2.module+el8.1.0+4044+36416a77.x86_64 (squid:4) as a component of Red Hat Enterprise Linux AppStream AUS (v. 8.2)
  • libecap-devel-0:1.0.1-2.module+el8.1.0+4044+36416a77.x86_64 (squid:4) as a component of Red Hat Enterprise Linux AppStream AUS (v. 8.2)
  • squid-7:4.4-8.module+el8.2.0+21527+aa63d5ff.9.src (squid:4) as a component of Red Hat Enterprise Linux AppStream AUS (v. 8.2)
  • squid-7:4.4-8.module+el8.2.0+21527+aa63d5ff.9.x86_64 (squid:4) as a component of Red Hat Enterprise Linux AppStream AUS (v. 8.2)
  • squid-debuginfo-7:4.4-8.module+el8.2.0+21527+aa63d5ff.9.x86_64 (squid:4) as a component of Red Hat Enterprise Linux AppStream AUS (v. 8.2)
  • squid-debugsource-7:4.4-8.module+el8.2.0+21527+aa63d5ff.9.x86_64 (squid:4) as a component of Red Hat Enterprise Linux AppStream AUS (v. 8.2)
  • libecap-0:1.0.1-2.module+el8.1.0+4044+36416a77.ppc64le (squid:4) as a component of Red Hat Enterprise Linux AppStream E4S (v. 8.2)
  • libecap-0:1.0.1-2.module+el8.1.0+4044+36416a77.src (squid:4) as a component of Red Hat Enterprise Linux AppStream E4S (v. 8.2)
  • libecap-0:1.0.1-2.module+el8.1.0+4044+36416a77.x86_64 (squid:4) as a component of Red Hat Enterprise Linux AppStream E4S (v. 8.2)
Summary
A flaw was found in Squid. This issue may allow a remote attacker to trigger an uncontrolled recursion bug when sending a specially crafted, chunked, encoded HTTP Message, resulting in a denial of service.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing this update, the squid service will be restarted automatically.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2024-22472

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Squid is a web proxy cache. Starting in version 3.5.27 and prior to version 6.8, Squid may be vulnerable to a Denial of Service attack against HTTP Chunked decoder due to an uncontrolled recursion bug. This problem allows a remote attacker to cause Denial of Service when sending a crafted, chunked, encoded HTTP Message. This bug is fixed in Squid version 6.8. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. There is no workaround for this issue.

What

Squid is a web proxy cache. Starting in version 3.5.27 and prior to version 6.8, Squid may be vulnerable to a Denial of Service attack against HTTP Chunked decoder due to an uncontrolled recursion bug. This problem allows a remote attacker to cause Denial of Service when sending a crafted, chunked, encoded HTTP Message. This bug is fixed in Squid version 6.8. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. There is no workaround for this issue.

Why

The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

Squid is a web proxy cache. Starting in version 3.5.27 and prior to version 6.8, Squid may be vulnerable to a Denial of Service attack against HTTP Chunked decoder due to an uncontrolled recursion bug. This problem allows a remote attacker to cause Denial of Service when sending a crafted, chunked, encoded HTTP Message. This bug is fixed in Squid version 6.8. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. There is no workaround for this issue.

Why

The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

CISA Vulnrichment records proof-of-concept exploitation in its SSVC data. BlackTree has not independently executed or validated exploit material.

Likely attack path
a network path → Uncontrolled Recursion → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Changed: exploitation can affect a different security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-674 ↗

CWE-674: Uncontrolled Recursion. The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SChangedScope: The attack can affect a component governed by a different security authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of serviceCWE-674Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2024-0544Squid: Schwachstelle ermöglicht Denial of Service

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Squid ausnutzen, um einen Denial of Service Angriff durchzuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20240313Security Bulletin 13 Mar 2024

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 13 Mar 2024, published on 13 March 2024. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0182Vulnérabilité dans les produits Squid

Une vulnérabilité a été découverte dans les produits Squid . Elle permet à un attaquant de provoquer un déni de service à distance.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2024-019391Squid-cache.org の Squid 等複数ベンダの製品における再帰制御に関する脆弱性

Squid-cache.org の Squid 等複数ベンダの製品には、再帰制御に関する脆弱性が存在します。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
squid: >= 3.5.27, < 6.8
Fixed
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing this update, the squid service will be restarted automatically.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 6 Mar 2024 · Last source change 3 Nov 2025, 20:36 UTC · CWE-674 · Uncontrolled Recursion

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2024-22472
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    >= 3.5.27, < 6.8 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    >= 3.5.27, < 6.8 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing this update, the squid service will be restarted automatically.
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2024-22472↗Red Hat Product Security security advisory↗CISA Vulnrichment SSVC evidence↗CVE authority or vendor reference · GitHub GHSA-72C2-C3WM-8QXC↗Patch or update reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2024-25111 · cve.blacktree.nl