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CVE-2026-115506

libexpat through 2.9.0 Denial of Service via Billion Laughs Detection Delay

Published: 10/22/2026 Last updated: 10/23/2026 Reserved: 10/22/2026

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.

CNA assigner: VulnCheck (83251b91-4cc7-4094-a5c7-464a1b83ea10) Requested by: n/a

Metrics

Version Score Severity Vector String
4.0 8.7 High 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
3.1 7.5 High CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Opam packages affected (4)

conf-expat conf-gtk2 conf-gtk3 ocaml-expat

Products affected (0)

No product listed.

References (5)

Credits (2)