CVE-2009-3720

Medium

Published: 03/11/2009(UTC)Updated: 20/07/2026(UTC)Translated: 21/07/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Very high risk

27.92%

98th percentile - higher than 98% of all known CVEs

Summary

The updatePosition function in libexpat (Expat 2.0.1) has a buffer over-read vulnerability. Crafted UTF-8 sequences in an XML document can cause an application crash.

Risk Assessment

An attacker can remotely cause a denial of service (DoS) by sending a malicious XML document to an application using the vulnerable Expat version, potentially disrupting system operations.

Recommendation

Update the Expat library to version 2.0.2 or later, and update all dependent software (Python, PyXML, w3c-libwww).

Original NVD description (English source)

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.