Advisories

libexpat through 2.9.0 Denial of Service via Billion Laughs Detection Delay

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Severity
high
Date
Affecting
  • libexpat <= 2.9.0

CWE
  • CWE-776 Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
CVSS
8.7
CVSS V4 Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Credit
Hanno Böck, Shani Yosef
Description
libexpat through 2.9.0 contains a denial of service vulnerability because billion laughs protection in accountingDiffTolerated() in xmlparse.c detects entity amplification too late. Attackers can supply a moderately sized XML document with a large DTD and nested entity expansions to consume tens of seconds of CPU per parse.

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