CVE-2026-115506
libexpat through 2.9.0 Denial of Service via Billion Laughs Detection Delay
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-776 |
| Vendor | libexpat |
| Product | libexpat |
| Published | Oct 22, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
libexpat / libexpat
0 ≤ 2.9.0
References
github.com: https://github.com/libexpat/libexpat/pull/1433 github.com: https://github.com/libexpat/libexpat/issues/1160 github.com: https://github.com/hannob/lololol github.com: https://github.com/libexpat/libexpat vulncheck.com: https://www.vulncheck.com/advisories/libexpat-through-2.9.0-denial-of-service-via-billion-laughs-detection-delay
Credits
Hanno Böck Shani Yosef