CVE-2009-3720: Apache HTTP Server

Medium severity, CVSS 5.0. EPSS: 27.9% chance of exploitation in the next 30 days.

The updatePosition function in lib/xmltok_impl.c in libexpat in Expat 2.0.1, as used in Python, PyXML, w3c-libwww, and other software, allows context-dependent attackers to cause a denial of service (application crash) via an XML document with crafted UTF-8 sequences that trigger a buffer over-read, a different vulnerability than CVE-2009-2625.

Affected products

• Apache HTTP Server: from 2.0.35, before 2.0.64 (fixed in 2.0.64); from 2.2.0, before 2.2.17 (fixed in 2.2.17)
• Libexpat Project Libexpat: version 2.0.1 only

Published 2009-11-03. Last modified 2026-07-20.