CVE-2021-28651

Publication date 27 May 2021

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to a buffer-management bug, it allows a denial of service. When resolving a request with the urn: scheme, the parser leaks a small amount of memory. However, there is an unspecified attack methodology that can easily trigger a large amount of memory consumption.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
squid	24.04 LTS noble	Fixed 4.13-10ubuntu1
	23.10 mantic	Fixed 4.13-10ubuntu1
	23.04 lunar	Fixed 4.13-10ubuntu1
	22.10 kinetic	Fixed 4.13-10ubuntu1
	22.04 LTS jammy	Fixed 4.13-10ubuntu1
	21.10 impish	Fixed 4.13-10ubuntu1
	21.04 hirsute	Fixed 4.13-1ubuntu4.1
	20.10 groovy	Fixed 4.13-1ubuntu2.2
	20.04 LTS focal	Fixed 4.10-1ubuntu1.4
	18.04 LTS bionic	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
squid3	24.04 LTS noble	Not in release
	23.10 mantic	Not in release
	23.04 lunar	Not in release
	22.10 kinetic	Not in release
	22.04 LTS jammy	Not in release
	21.10 impish	Not in release
	21.04 hirsute	Not in release
	20.10 groovy	Not in release
	20.04 LTS focal	Not in release
	18.04 LTS bionic	Fixed 3.5.27-1ubuntu1.11
	16.04 LTS xenial	Fixed 3.5.12-1ubuntu7.16+esm3
	14.04 LTS trusty	Not in release

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Patch details

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

Package	Patch details
squid	Upstream: http://www.squid-cache.org/Versions/v4/changesets/squid-4-a975fd5aedc866629214aaaccb38376855351899.patch Upstream: a975fd5

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