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Servers and applications

CVE-2009-3720

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.

Severity
Medium 5.0
Published
3 Nov 2009
Last changed
20 Jul 2026
Added to UpHeron
17 Oct 2026
Fixed in
2.0.64, 2.2.17
Exploit chance
28% in the next 30 daysHigher than 98% of CVEs. EPSS by FIRST, 12 Nov 2026
Attack
Over the network · No login needed
Attacker can
Slow it down
CVSS vector
AV:N/AC:L/Au:N/C:N/I:N/A:P
Sources
NVD

Affected software

SoftwareAffected versions
Apache HTTP ServerServers and applications · cpe:a:apache:http_server
  • From 2.0.35 before 2.0.64
  • From 2.2.0 before 2.2.17
ExpatServers and applications · cpe:a:libexpat_project:libexpat
  • Version 2.0.1

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2009-3720
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2009-3720