High severity · published Oct 22, 2026
CVE-2026-115506
libexpat through 2.9.0 Denial of Service via Billion Laughs Detection Delay
New
7.5
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 39% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
libexpat · libexpat
through 2.9.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-115506
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-115506
github.com
https://github.com/hannob/lololol
github.com
https://github.com/libexpat/libexpat
github.com
https://github.com/libexpat/libexpat/issues/1160
github.com
https://github.com/libexpat/libexpat/pull/1433
www.vulncheck.com
https://www.vulncheck.com/advisories/libexpat-through-2.9.0-denial-of-service-via-billion-laughs-detection-delay
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