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prionPRIOn knowledge basePRION:CVE-2019-12521
HistoryApr 15, 2020 - 7:15 p.m.

Design/Logic Flaw

2020-04-1519:15:00
PRIOn knowledge base
www.prio-n.com
12

7.5 High

AI Score

Confidence

High

0.034 Low

EPSS

Percentile

91.4%

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.