CVE-2003-1564: Xmlsoft LIBXML2

Medium severity, CVSS 6.5. EPSS: 1.6% chance of exploitation in the next 30 days.

libxml2, possibly before 2.5.0, does not properly detect recursion during entity expansion, which allows context-dependent attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document containing a large number of nested entity references, aka the "billion laughs attack."

Affected products

• Xmlsoft LIBXML2: before 2.5.0 (fixed in 2.5.0)

Published 2003-12-31. Last modified 2026-06-16.