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20Track

libexpat through 2.9.0 Denial of Service via Billion Laughs Detection Delay

libexpat · CVE-2026-115506
0 news outlets0 CERTs and agencies1 research labs

Assessment: Track

SSVC decision points: exploitation poc, automatable yes, technical impact partial, deployment low.

What is it?

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.

Evidence

Technical advisories1Detailed write-ups from security research teams

Exploitation

  • Exploit code published (not verified by us)
  • Exploited in the wild (confirmed by a source)
  • Listed as known exploited (CISA KEV)
CVSS
7.5
EPSS
0.5%
First seen
1 d ago
Status
corroborated

All libexpat vulnerabilities