CVE-2009-3720

NONECVSS 0.0Elevated

0.0

EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.

No confirmed exploitation signals yet

CISA-KEV: Not listedEPSS: 28%CVSS: —Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3: —
EG Score: 0.0(none)
EPSS: 97.9%
KEV: Not listed

Published

November 3, 2009

Last Modified

April 23, 2026

References (186)

secalert@redhathttp://expat.cvs.sourceforge.net/viewvc/expat/expat/lib/xmltok_impl.c?r1=1.13&r2=1.15&view=patch
secalert@redhathttp://expat.cvs.sourceforge.net/viewvc/expat/expat/lib/xmltok_impl.c?view=log
secalert@redhathttp://lists.fedoraproject.org/pipermail/package-announce/2010-November/051228.html
secalert@redhathttp://lists.fedoraproject.org/pipermail/package-announce/2010-November/051247.html
secalert@redhathttp://lists.fedoraproject.org/pipermail/package-announce/2010-November/051367.html
secalert@redhathttp://lists.fedoraproject.org/pipermail/package-announce/2010-November/051405.html
secalert@redhathttp://lists.fedoraproject.org/pipermail/package-announce/2010-November/051442.html
secalert@redhathttp://lists.opensuse.org/opensuse-security-announce/2009-11/msg00004.html
secalert@redhathttp://lists.opensuse.org/opensuse-security-announce/2010-05/msg00001.html
secalert@redhathttp://lists.opensuse.org/opensuse-security-announce/2010-05/msg00002.html
secalert@redhathttp://lists.opensuse.org/opensuse-security-announce/2010-06/msg00001.html
secalert@redhathttp://lists.opensuse.org/opensuse-security-announce/2010-08/msg00001.html
secalert@redhathttp://lists.vmware.com/pipermail/security-announce/2010/000082.html
secalert@redhathttp://mail.python.org/pipermail/expat-bugs/2009-January/002781.html
secalert@redhathttp://marc.info/?l=bugtraq&m=130168502603566&w=2

Vendor Advisories for CVE-2009-3720(4)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(13)

Vendor / Ecosystem	Fixed in / Patch	Released	Source
ubuntu	python2.5 (2.5.2-11.1ubuntu1.1) @ intrepid	2026-05-30	ubuntu
ubuntu	python2.4 (2.4.6-1ubuntu3.2.9.10.1) @ karmic	2026-05-30	ubuntu
ubuntu	libexpat1 (2.0.1-4ubuntu1.1) @ karmic	2026-05-30	ubuntu
ubuntu	cmake (2.6.2-1ubuntu1.1) @ jaunty	2026-05-30	ubuntu
ubuntu	python2.4-xml (0.8.4-1ubuntu3.1) @ dapper	2026-05-30	ubuntu
ubuntu	libxmlrpc-core-c3 (1.06.27-1ubuntu6.1) @ karmic	2026-05-30	ubuntu
redhat	patch	2017-11-16	redhat
redhat	patch	2011-06-22	redhat
redhat	python-0:2.4.3-44.el5	2011-05-05	redhat
redhat	python-0:2.3.4-14.10.el4	2011-05-05	redhat
redhat	PyXML-0:0.8.4-4.el5_4.2	2010-01-04	redhat
redhat	expat-0:1.95.8-8.3.el5_4.2	2009-12-07	redhat
redhat	4Suite-0:1.0-3.el4_8.1	2009-11-10	redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Additional Vendor Advisories

(9)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 6× in last 7d / 36× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

2026-07-07 15:11 UTCOSV refresh
2026-07-06 16:23 UTCEPSS rescore
2026-07-05 02:26 UTCEPSS rescore
2026-07-05 02:26 UTCEPSS rescore
2026-07-01 15:02 UTCEPSS rescore
2026-06-30 23:19 UTCEPSS rescore
2026-06-29 14:02 UTCEPSS rescore
2026-06-29 14:02 UTCEPSS rescore
2026-06-28 14:03 UTCEPSS rescore
2026-06-28 04:52 UTCEPSS rescore
2026-06-28 04:52 UTCEPSS rescore
2026-06-27 03:05 UTCEPSS rescore
2026-06-25 13:46 UTCEPSS rescore
2026-06-25 13:46 UTCEPSS rescore
2026-06-24 14:02 UTCEPSS rescore
2026-06-24 14:02 UTCEPSS rescore
2026-06-23 21:29 UTCEPSS rescore
2026-06-23 21:29 UTCEPSS rescore
2026-06-21 01:56 UTCEPSS rescore
2026-06-21 01:56 UTCEPSS rescore
2026-06-19 02:35 UTCOSV refresh
2026-06-18 17:49 UTCEPSS rescore
2026-06-18 17:49 UTCEPSS rescore
2026-06-17 17:49 UTCEPSS rescore
2026-06-17 17:49 UTCEPSS rescore

Show 48 more

2026-06-16 17:49 UTCEPSS rescore
2026-06-16 17:49 UTCEPSS rescore
2026-06-15 17:44 UTCEPSS rescore
2026-06-14 23:14 UTCEPSS rescore
2026-06-14 23:14 UTCEPSS rescore
2026-06-13 22:57 UTCEPSS rescore
2026-06-12 23:08 UTCEPSS rescore
2026-06-12 23:08 UTCEPSS rescore
2026-06-10 22:14 UTCEPSS rescore
2026-06-10 13:17 UTCEPSS rescore
2026-06-08 14:13 UTCEPSS rescore
2026-06-07 15:22 UTCEPSS rescore
2026-06-07 15:22 UTCEPSS rescore
2026-06-05 22:44 UTCEPSS rescore
2026-06-05 22:44 UTCEPSS rescore
2026-06-05 06:07 UTCEPSS rescore
2026-06-04 13:09 UTCEPSS rescore
2026-06-04 13:09 UTCEPSS rescore
2026-06-02 20:10 UTCEPSS rescore
2026-06-02 20:10 UTCEPSS rescore
2026-06-01 13:49 UTCEPSS rescore
2026-06-01 13:49 UTCEPSS rescore
2026-05-31 22:28 UTCEPSS rescore
2026-05-31 22:28 UTCEPSS rescore
2026-05-31 00:13 UTCEPSS rescore
2026-05-31 00:13 UTCEPSS rescore
2026-05-30 14:43 UTCEG score recompute
2026-05-30 14:43 UTCVendor advisory
2026-05-30 14:43 UTCGHSA enrichment
2026-05-29 13:40 UTCEPSS rescore
2026-05-28 13:42 UTCEPSS rescore
2026-05-28 13:42 UTCEPSS rescore
2026-05-28 13:42 UTCEPSS rescore
2026-05-27 13:38 UTCEPSS rescore
2026-05-27 13:38 UTCEPSS rescore
2026-05-26 13:41 UTCEPSS rescore
2026-05-26 13:41 UTCEPSS rescore
2026-05-26 07:16 UTCEPSS rescore
2026-05-26 07:16 UTCEPSS rescore
2026-05-24 16:43 UTCEPSS rescore
2026-05-22 21:15 UTCEPSS rescore
2026-05-22 21:15 UTCEPSS rescore
2026-05-22 03:06 UTCOSV refresh
2026-05-20 22:37 UTCEPSS rescore
2026-05-20 22:37 UTCEPSS rescore
2026-05-20 11:21 UTCEPSS rescore
2026-05-20 11:20 UTCEPSS rescore
2026-05-18 21:29 UTCEPSS rescore

Same vendor

10 shown

redhat

Frequently asked(4)

What is CVE-2009-3720?

CVE-2009-3720 is a none vulnerability published on November 3, 2009. 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…

When was CVE-2009-3720 disclosed?

CVE-2009-3720 was first published in the National Vulnerability Database on November 3, 2009, with the most recent update on April 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2009-3720 actively exploited?

CVE-2009-3720 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 97.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

How do I remediate CVE-2009-3720?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2009-3720, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2009-3720

Explore →

Is Your Infrastructure Affected by CVE-2009-3720?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs

CVE-2009-3720

📅 Published

🔄 Last Modified

🔗 References (186)

📣 Vendor Advisories for CVE-2009-3720(4)