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.
A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.
| Link | Tags |
|---|---|
| https://gitlab.com/jeriko.one/security/-/blob/master/squid/CVEs/CVE-2019-12521.txt | third party advisory |
| http://www.openwall.com/lists/oss-security/2020/04/23/1 | mailing list third party advisory patch |
| https://www.debian.org/security/2020/dsa-4682 | third party advisory vendor advisory |
| http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00018.html | mailing list third party advisory vendor advisory |
| https://security.gentoo.org/glsa/202005-05 | third party advisory vendor advisory |
| https://usn.ubuntu.com/4356-1/ | third party advisory vendor advisory |
| https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html | third party advisory mailing list |
| https://security.netapp.com/advisory/ntap-20210205-0006/ | third party advisory |