CVE-2023-5824

Squid: dos against http and https

Published Nov 3, 2023 CVSS 3.1 · 7.5 High EPSS 3.3% KEV · Not listed
Description
A 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.

Remediation

Vendor Workaround

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.

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4312-1 squid security update
Debian DSA Debian DSA DSA-5982-1 squid security update
EUVD EUVD EUVD-2023-58107 A 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.
Ubuntu USN Ubuntu USN USN-6728-1 Squid vulnerabilities
Ubuntu USN Ubuntu USN USN-6728-3 Squid vulnerability
History
Type Values Removed Values Added
First Time appeared Redhat rhel Els
CPEs cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:rhel_els:6
cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat rhel Els
Type Values Removed Values Added
Description Squid is vulnerable to Denial of Service attack against HTTP and HTTPS clients due to an Improper Handling of Structural Elements bug. A 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.
Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Nov 4, 2026, 9:06 PM
Reserved
Oct 27, 2023, 9:37 AM
Status
Modified
Published
Nov 3, 2023, 8:15 AM
Modified
Nov 4, 2026, 9:17 PM
Severity
Important
Public date
Oct 19, 2023, 12:00 AM