vulnerability
Red Hat: CVE-2019-12521: CVE-2019-12521 squid: Off-by-one error in addStackElement allows for heap buffer overflow and crash (Multiple Advisories)
| Severity | CVSS | Published | Added | Modified |
|---|---|---|---|---|
| 4 | (AV:N/AC:M/Au:N/C:N/I:N/A:P) | Apr 15, 2020 | Nov 5, 2020 | Aug 11, 2025 |
Severity
4
CVSS
(AV:N/AC:M/Au:N/C:N/I:N/A:P)
Published
Apr 15, 2020
Added
Nov 5, 2020
Modified
Aug 11, 2025
Description
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.
Solutions
no-fix-redhat-rpm-packageredhat-upgrade-libecapredhat-upgrade-libecap-debuginforedhat-upgrade-libecap-debugsourceredhat-upgrade-libecap-develredhat-upgrade-squidredhat-upgrade-squid-debuginforedhat-upgrade-squid-debugsource
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