CVE-2023-5824

Publication date 3 November 2023

Last updated 4 August 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

7.5 · High

Score breakdown

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.

Read the notes from the security team

Status

Package Ubuntu Release Status
squid 25.04 plucky
Fixed 6.5-1ubuntu1
24.10 oracular
Fixed 6.5-1ubuntu1
24.04 LTS noble
Fixed 6.5-1ubuntu1
23.10 mantic
Fixed 6.1-2ubuntu1.3
23.04 lunar Ignored end of life, was deferred [2024-01-26]
22.04 LTS jammy
Fixed 5.7-0ubuntu0.22.04.4
20.04 LTS focal
Fixed 4.10-1ubuntu1.12
18.04 LTS bionic Ignored end of standard support
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Ignored end of standard support
squid3 25.04 plucky Not in release
24.10 oracular Not in release
24.04 LTS noble Not in release
23.10 mantic Not in release
23.04 lunar Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Vulnerable
16.04 LTS xenial
Vulnerable
14.04 LTS trusty Ignored end of standard support

Notes

mdeslaur

as of 2024-01-26, this is not fixed in the upstream 5.x repository. The patches to fix this issue are large and intrusive. Per the researcher's advisory, "Of course, such 'attacks' are completely theoretical and are only considered for entertainment purposes." Ubuntu 20.04 LTS was patched in USN-6728-1, but the fix introduced crashes and was backed out in USN-6728-2. It was ultimately fixed in USN-6728-3.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
squid

Severity score breakdown

Parameter Value
Base score 7.5 · High
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H