QID 356292

a flaw was found in squid through version 4.7.
When handling the tag esi:when, when esi is enabled, squid calls the esiexpression::evaluate function which uses a fixed stack buffer to hold the expression.
While processing the expression, there is no check to ensure that the stack wont overflow.
The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability. (
( CVE-2019-12519) a flaw was found in squid.
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 its off by 1, leading to a heap overflow of 1 element.
The overflow is within the same structure so it cant affect adjacent memory blocks, and thus just leads to a crash while processing. (
( CVE-2019-12521) an issue was discovered in squid 3.3.9 through 3.5.28 and 4.x through 4.7.
When squid is configured to use digest authentication, it parses the header proxy-authorization.
It searches for certain tokens such as domain, uri, and qop.
Squid checks if this tokens value starts with a quote and ends with one.
If so, it performs a memcpy of its length minus 2.
Squid never checks whether the value is just a single quote (which would satisfy its requirements), leading to a memcpy of its length minus 1. (
( CVE-2019-12525) a flaw was found in squid, where a remote attacker can replay a sniffed digest authentication nonce to gain access to resources that are otherwise forbidden.
( CVE-2020-11945)

Successful exploitation of this vulnerability could lead to a securitybreach or could affect integrity, availability, and confidentiality.