Arch Linux Security Advisory ASA-201911-8
========================================
Severity: Critical
Date    : 2019-11-07
CVE-ID  : CVE-2019-12526 CVE-2019-18678 CVE-2019-18679
Package : squid
Type    : multiple issues
Remote  : Yes
Link    : https://security.archlinux.org/AVG-1062

Summary
======
The package squid before version 4.9-1 is vulnerable to multiple issues
including arbitrary code execution, content spoofing and information
disclosure.

Resolution
=========
Upgrade to 4.9-1.

# pacman -Syu "squid>=4.9-1"

The problems have been fixed upstream in version 4.9.

Workaround
=========
- CVE-2019-12526

Deny urn: protocol URI being proxied to all clients:

    acl URN proto URN
    http_access deny URN

- CVE-2019-18678

There are no workarounds for this vulnerability.

- CVE-2019-18679

Digest authentication can be disabled by removing all 'auth_param
digest ...' configuration settings from squid.conf.

Description
==========
- CVE-2019-12526 (arbitrary code execution)

A heap-based buffer overflow has been found in Squid before 4.9, when
processing URN.

- CVE-2019-18678 (content spoofing)

A HTTP request splitting issue has been found in Squid before 4.9. This
issue allows attackers to smuggle HTTP requests through frontend
software to a Squid which splits the HTTP Request pipeline differently.
The resulting Response messages corrupt caches between client and Squid
with attacker controlled content at arbitrary URLs.

- CVE-2019-18679 (information disclosure)

An information disclosure issue has been found in Squid before 4.9,
when processing HTTP Digest Authentication. The nonce tokens contain
the raw byte value of a pointer which sits within heap memory
allocation, which reduces ASLR protections and may aid attackers
isolating memory areas to target for remote code execution attacks.

Impact
=====
A remote attacker might access sensitive information, corrupt the
content of arbitrary URLs in the caches or execute arbitrary code.

References
=========
http://www.squid-cache.org/Advisories/SQUID-2019_7.txt
http://www.squid-cache.org/Advisories/SQUID-2019_10.txt
http://www.squid-cache.org/Advisories/SQUID-2019_11.txt
https://security.archlinux.org/CVE-2019-12526
https://security.archlinux.org/CVE-2019-18678
https://security.archlinux.org/CVE-2019-18679