SB2020042377 - Multiple vulnerabilities in Squid Proxy Cache

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Main Vulnerability Database SB2020042377

SB2020042377 - Multiple vulnerabilities in Squid Proxy Cache

Published: April 23, 2020 Updated: May 11, 2020

Security Bulletin ID SB2020042377
Severity
High
Patch available
YES
Number of vulnerabilities 3
Exploitation vector Remote access
Highest impact Code execution

Breakdown by Severity

High 67% Medium 33%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 3 secuirty vulnerabilities.


1) Integer overflow (CVE-ID: CVE-2020-11945)

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to integer overflow when processing HTTP Digest Authentication tokens, if memory pooling is disabled. A remote attacker can pass a specially crafted authentication nonce and execute arbitrary code on the server through the free'd nonce credentials.

In case memory pooling is enabled, a remote attacker can replay a sniffed Digest Authentication nonce to gain access  to resources that are otherwise forbidden.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.



2) Out-of-bounds write (CVE-ID: CVE-2019-12519)

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a boundary error when handling the tag esi:when within ESIExpression::Evaluate. A remote attacker can pass specially crafted data to the application, trigger out-of-bounds write and execute arbitrary code on the target system.


3) Out-of-bounds write (CVE-ID: CVE-2019-12521)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a boundary error when processing untrusted input. 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.


Remediation

Install update from vendor's website.

References