CVE-2023-5824: Squid: dos against http and https

Published Oct 24, 2023
·
Updated

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.

Other sources

Description: a) Due to an Improper Handling of Structural Elements bug Squid is vulnerable to a Denial of Service attack against HTTP and HTTPS clients.

b) Due to an Incomplete Filtering of Special Elements bug Squid is vulnerable to a Denial of Service attack against HTTP and HTTPS clients.

Reference: https://github.com/squid-cache/squid/security/advisories/GHSA-543m-w2m2-g255

Affected versions: < 6.4

Red Hat

Squid is vulnerable to Denial of Service attack against HTTP and HTTPS clients due to an Improper Handling of Structural Elements bug.

Launchpad

Affected Software

8 affected componentsFixes available
redhat/squid<6.4
6.4
Squid-Cache Squid<6.4
redhat Enterprise Linux=6.0
redhat Enterprise Linux=7.0
redhat Enterprise Linux=8.0
redhat Enterprise Linux=9.0
debian/squid<=4.13-10+deb11u3, <=5.7-2+deb12u2
6.13-1
Microsoft azl3 squid 6.13-1

Event History

Nov 3, 2023
CVE Published
via MITRE·07:56 AM
Data Sourced
via MITRE·07:56 AM
DescriptionSeverityWeakness
Data Sourced
via NVD·08:15 AM
DescriptionSeverityWeaknessAffected Software
May 4, 2024
Data Sourced
via Launchpad·05:43 PM
Description
Sep 15, 2024
Data Sourced
via Ubuntu·05:07 AM
RemedyDescriptionSeverityAffected Software
Sep 4, 2025
Data Sourced
via Microsoft·05:25 AM
DescriptionSeverityWeakness
Data Sourced
via Microsoft·05:25 AM
Affected Software
Updated
via Microsoft·05:25 AM
DescriptionSeverity

Frequently Asked Questions

1

What is the vulnerability ID for this Squid vulnerability?

The vulnerability ID for this Squid vulnerability is CVE-2023-5824.

2

What is the title of this vulnerability?

The title of this vulnerability is 'Squid: dos against http and https'.

3

What is the description of this vulnerability?

The description of this vulnerability is 'Squid is vulnerable to Denial of Service attack against HTTP and HTTPS clients due to an Improper Handling of Structural Elements bug.'

4

What is the severity rating of this vulnerability?

The severity rating of this vulnerability is critical (9.6).

5

What software is affected by this vulnerability?

The affected software is Squid version up to (but not including) 6.4, Redhat Enterprise Linux versions 6.0 to 9.0.

6

Where can I find more information about this vulnerability?

More information about this vulnerability can be found at the following references: [1](https://access.redhat.com/security/cve/CVE-2023-5824), [2](https://bugzilla.redhat.com/show_bug.cgi?id=2245914), [3](https://github.com/squid-cache/squid/security/advisories/GHSA-543m-w2m2-g255).

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203