Bug 1770356 (CVE-2019-12526)

Summary:	CVE-2019-12526 squid: Heap overflow issue in URN processing
Product:	[Other] Security Response	Reporter:	Pedro Sampaio <psampaio>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	anon.amish, code, jonathansteffan, luhliari, momran, uwe.knop, yozone
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	squid 4.9	Doc Type:	If docs needed, set a value
Doc Text:	A heap-based buffer overflow was found in the way squid processed certain Uniform Resource Names (URNs). A remote attacker could use this flaw to cause Squid to crash or execute arbitrary code with the permissions of the user running Squid.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-11-04 02:22:59 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1770357, 1771263, 1771264
Bug Blocks:	1770358

Description Pedro Sampaio 2019-11-08 19:50:22 UTC

Due to incorrect buffer management Squid is vulnerable to a heap overflow and possible remote code execution attack when processing URN.

References:

http://www.squid-cache.org/Advisories/SQUID-2019_7.txt

Comment 1 Pedro Sampaio 2019-11-08 19:50:36 UTC

Created squid tracking bugs for this issue:

Affects: fedora-all [bug 1770357]

Comment 2 Huzaifa S. Sidhpurwala 2019-11-12 04:53:18 UTC

External References:

http://www.squid-cache.org/Advisories/SQUID-2019_7.txt

Comment 3 Huzaifa S. Sidhpurwala 2019-11-12 04:53:21 UTC

Mitigation:

The following mitigation is suggested by upstream:

Deny urn: protocol URI being proxied to all clients:
~~~
    acl URN proto URN
    http_access deny URN
~~~

Comment 4 Huzaifa S. Sidhpurwala 2019-11-12 05:05:49 UTC

Analysis:

This is a heap-based buffer overflow, which can be triggered by a malicious client. The client can overwrite substantial amount of heap potentially causing squid to crash or even execute arbitrary code with the permissions of the user running squid (normally squid user which is non-privileged). Also on Red Hat Products, squid is confined with selinux which should reduce the possibilities of code execution.

Because of the above mentioned difficulties in exploitation, Red Hat Product Security has classified this flaw as having Moderate impact.

Comment 5 Huzaifa S. Sidhpurwala 2019-11-12 05:05:52 UTC

Statement:

This is a heap-based buffer overflow, which can be triggered by a malicious client. The client can overwrite substantial amount of heap potentially causing squid to crash or even execute arbitrary code with the permissions of the user running squid (normally squid user which is non-privileged). Also on Red Hat Products, squid is confined with selinux which should reduce the possibilities of code execution.

Because of the above mentioned difficulties in exploitation, Red Hat Product Security has classified this flaw as having Moderate impact.

Comment 7 Huzaifa S. Sidhpurwala 2019-11-12 05:15:10 UTC

Upstream patch: http://www.squid-cache.org/Versions/v4/changesets/squid-4-7aa0184a720fd216191474e079f4fe87de7c4f5a.patch

Comment 8 Product Security DevOps Team 2020-11-04 02:22:59 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2019-12526

Comment 9 errata-xmlrpc 2020-11-04 03:31:19 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2020:4743 https://access.redhat.com/errata/RHSA-2020:4743