CVE-2019-12521

Publication date 15 April 2020

Last updated 25 August 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

5.9 · Medium

Score breakdown

Description

An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.

Status

Package Ubuntu Release Status
squid 21.04 hirsute
Fixed 4.10-1ubuntu2
20.10 groovy
Fixed 4.10-1ubuntu2
20.04 LTS focal
Fixed 4.10-1ubuntu1.1
19.10 eoan
Fixed 4.8-1ubuntu2.3
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
squid3 21.04 hirsute Not in release
20.10 groovy Not in release
20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Fixed 3.5.27-1ubuntu1.6
16.04 LTS xenial
Fixed 3.5.12-1ubuntu7.11
14.04 LTS trusty Not in release

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 5.9 · Medium
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

Other references