Squid: dos against http and https

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Summary

CVECVE-2023-5824
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2023-11-03 08:15:08 UTC
Updated2026-11-04 21:17:26 UTC
DescriptionA flaw was found in Squid. The limits applied for validation of HTTP response headers are applied before caching. However, Squid may grow a cached HTTP response header beyond the configured maximum size, causing a stall or crash of the worker process when a large header is retrieved from the disk cache, resulting in a denial of service.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.032840000 probability, percentile 0.884980000 (date 2026-11-04)

Problem Types: CWE-755 | CWE-755 Improper Handling of Exceptional Conditions

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Redhat Enterprise Linux 6.0 All All All
Operating System Redhat Enterprise Linux 7.0 All All All
Operating System Redhat Enterprise Linux 8.0 All All All
Operating System Redhat Enterprise Linux 9.0 All All All
Application Squid-cache Squid All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Enterprise Linux 8 unaffected 8090020231130092412.a75119d5 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.2 Advanced Update Support unaffected 8020020240122164331.4cda2c84 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.2 Telecommunications Update Service unaffected 8020020240122164331.4cda2c84 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.2 Update Services For SAP Solutions unaffected 8020020240122164331.4cda2c84 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support unaffected 8040020240122165847.522a0ee4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Telecommunications Update Service unaffected 8040020240122165847.522a0ee4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Update Services For SAP Solutions unaffected 8040020240122165847.522a0ee4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support unaffected 8060020231222131040.ad008a3a * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Extended Update Support unaffected 8080020231222130009.63b34585 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9 unaffected 7:5.5-6.el9_3.2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.0 Extended Update Support unaffected 7:5.2-1.el9_0.4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.2 Extended Update Support unaffected 7:5.5-5.el9_2.3 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 7 Not specified Not specified

References

ReferenceSourceLinkTags
access.redhat.com/errata/RHSA-2024:1153 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
access.redhat.com/errata/RHSA-2023:7668 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
Red Hat af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
lists.debian.org/debian-lts-announce/2025/09/msg00027.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
security.netapp.com/advisory/ntap-20231130-0003 af854a3a-2127-422b-91ae-364da2661108 security.netapp.com
access.redhat.com/errata/RHSA-2024:0773 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
access.redhat.com/errata/RHSA-2024:0771 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
SQUID-2023:2 Multiple issues in HTTP response caching · Advisory · squid-cache/squid · GitHub af854a3a-2127-422b-91ae-364da2661108 github.com Vendor Advisory
access.redhat.com/errata/RHSA-2023:7465 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
access.redhat.com/errata/RHSA-2024:0772 af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
2245914 – (CVE-2023-5824) CVE-2023-5824 squid: DoS against HTTP and HTTPS af854a3a-2127-422b-91ae-364da2661108 bugzilla.redhat.com Issue Tracking
cve-details af854a3a-2127-422b-91ae-364da2661108 access.redhat.com Third Party Advisory
Red Hat af854a3a-2127-422b-91ae-364da2661108 access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
CNA2023-10-24T00:00:00.000ZReported to Red Hat.
CNA2023-10-19T00:00:00.000ZMade public.

Workarounds

CNA: Disabling the disk caching mechanism will mitigate this vulnerability. To achieve this, remove all the 'cache_dir' directives from the Squid configuration, typically in the /etc/squid/squid.conf file.

Legacy QID Mappings

  • 161198 Oracle Enterprise Linux Security Update for squid (ELSA-2023-7465)
  • 161218 Oracle Enterprise Linux Security Update for squid:4 (ELSA-2023-7668)
  • 200247 Ubuntu Security Notification for Squid Vulnerabilities (USN-6728-1)
  • 242506 Red Hat Update for squid (RHSA-2023:7465)
  • 242549 Red Hat Update for squid:4 (RHSA-2023:7668)
  • 242863 Red Hat Update for squid:4 (RHSA-2024:0397)
  • 242910 Red Hat Update for squid (RHSA-2024:0072)
  • 242913 Red Hat Update for squid:4 (RHSA-2024:0773)
  • 242914 Red Hat Update for squid:4 (RHSA-2024:0771)
  • 242915 Red Hat Update for squid:4 (RHSA-2024:0772)
  • 243018 Red Hat Update for squid (RHSA-2024:1153)
  • 296108 Oracle Solaris 11.4 Support Repository Update (SRU) 66.164.1 Missing (CPUJAN2024)
  • 357373 Amazon Linux Security Advisory for squid : ALAS2023-2024-578
  • 379621 Alibaba Cloud Linux Security Update for squid:4 (ALINUX3-SA-2024:0020)
  • 941421 AlmaLinux Security Update for squid (ALSA-2023:7465)
  • 941492 AlmaLinux Security Update for squid:4 (ALSA-2023:7668)
  • 961086 Rocky Linux Security Update for squid:4 (RLSA-2023:7668)

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