CVE-2009-3720

MEDIUMCVSS v2 · 5.05.0—
EchelonGraph scoreLOW confidence

This CVE was only ever scored under CVSS v2.0. NVD CVSS v2.0 base 5.0 — v2 rates that MEDIUM (v2 bands: LOW 0.0–3.9 / MEDIUM 4.0–6.9 / HIGH 7.0–10.0; v2 has no CRITICAL band). Vector AV:N/AC:L/Au:N/C:N/I:N/A:P. CVSS v2 is an older, coarser metric than v3.1/v4.0 (no Scope, no User Interaction, no Attack Requirements), so it is not directly comparable to a v3 or v4 score. NVD has never re-scored this record under v3. EPSS predicts 27.9% exploitation probability in the next 30 days, which is reflected in EG Risk but does not lift the v2 base. Confidence: LOW.

Sources: epss, nvd_v2
Elevated
5.0EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 28%CVSS v2: 5.0Exploit: Elevated riskExposed: 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 v2.0 (legacy)
5.0MEDIUMNVD never assigned a CVSS v3 rating to this CVE
EG Score
5.0(low)
EG Risk
43(Track)
EG Risk 43/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity50% × 45%
Exploitation40% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
28%
EPSS %ILE
98%
KEV
Not listed

Published

November 3, 2009

Last Modified

July 20, 2026

References (186)

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 / EcosystemFixed in / PatchReleasedSource
ubuntupython2.5 (2.5.2-11.1ubuntu1.1) @ intrepid2026-05-30ubuntu
ubuntupython2.4 (2.4.6-1ubuntu3.2.9.10.1) @ karmic2026-05-30ubuntu
ubuntulibexpat1 (2.0.1-4ubuntu1.1) @ karmic2026-05-30ubuntu
ubuntucmake (2.6.2-1ubuntu1.1) @ jaunty2026-05-30ubuntu
ubuntupython2.4-xml (0.8.4-1ubuntu3.1) @ dapper2026-05-30ubuntu
ubuntulibxmlrpc-core-c3 (1.06.27-1ubuntu6.1) @ karmic2026-05-30ubuntu
redhatpatch2017-11-16redhat
redhatpatch2011-06-22redhat
redhatpython-0:2.4.3-44.el52011-05-05redhat
redhatpython-0:2.3.4-14.10.el42011-05-05redhat
redhatPyXML-0:0.8.4-4.el5_4.22010-01-04redhat
redhatexpat-0:1.95.8-8.3.el5_4.22009-12-07redhat
redhat4Suite-0:1.0-3.el4_8.12009-11-10redhat

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.

Affected Packages

(50 across 6 ecosystems)
Debian:11(12)
PackageVulnerable rangeFixed inDependents
audacity—1.3.2-1—
cadaver0.23.3-2.1 ... 0.28+dfsg-2 (10 versions)——
cmake—2.6.0-6—
coin3—4.0.0~CMake~6f54f1602475+ds1-1—
expat—2.0.1-5—
gdcm—2.0.14-2—
ghostscript—8.71~dfsg-2—
libxmltok1.2-4, 1.2-4.1, 1.2-4.1~exp1, 1.2-4.2——
matanza0.13+ds2-1, 0.13+ds2-2——
mcabber—0.10.0-1—
paraview—3.6.2-1—
poco—1.3.6p1-1—
Debian:12(12)
PackageVulnerable rangeFixed inDependents
audacity—1.3.2-1—
cadaver0.24+dfsg-1 ... 0.28+dfsg-2 (8 versions)——
cmake—2.6.0-6—
coin3—4.0.0~CMake~6f54f1602475+ds1-1—
expat—2.0.1-5—
gdcm—2.0.14-2—
ghostscript—8.71~dfsg-2—
libxmltok1.2-4, 1.2-4.1, 1.2-4.1~exp1, 1.2-4.2——
matanza0.13+ds2-1, 0.13+ds2-2——
mcabber—0.10.0-1—
paraview—3.6.2-1—
poco—1.3.6p1-1—
Debian:13(11)
PackageVulnerable rangeFixed inDependents
audacity—1.3.2-1—
cadaver0.26+dfsg-2, 0.28+dfsg-1, 0.28+dfsg-2——
cmake—2.6.0-6—
coin3—4.0.0~CMake~6f54f1602475+ds1-1—
expat—2.0.1-5—
gdcm—2.0.14-2—
ghostscript—8.71~dfsg-2—
matanza0.13+ds2-2——
mcabber—0.10.0-1—
paraview—3.6.2-1—
poco—1.3.6p1-1—
Debian:14(11)
PackageVulnerable rangeFixed inDependents
audacity—1.3.2-1—
cadaver0.26+dfsg-2, 0.28+dfsg-1, 0.28+dfsg-2——
cmake—2.6.0-6—
coin3—4.0.0~CMake~6f54f1602475+ds1-1—
expat—2.0.1-5—
gdcm—2.0.14-2—
ghostscript—8.71~dfsg-2—
matanza0.13+ds2-2——
mcabber—0.10.0-1—
paraview—3.6.2-1—
poco—1.3.6p1-1—
Debian:4.0(2)
PackageVulnerable rangeFixed inDependents
expat1.95.8-3.41.95.8-3.4+etch1—
python2.42.4.4-3, 2.4.4-3+etch1, 2.4.4-3+etch22.4.4-3+etch3—
Debian:5.0(2)
PackageVulnerable rangeFixed inDependents
expat2.0.1-42.0.1-4+lenny1—
python2.42.4.6-12.4.6-1+lenny1—

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 3× in last 7d / 8× 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.

Showing the most recent 100 of 105 total refreshes for this CVE.

  1. 2026-08-26 02:40 UTCOSV refresh
  2. 2026-08-25 13:43 UTCEPSS rescore
  3. 2026-08-19 16:58 UTCEPSS rescore
  4. 2026-08-15 01:24 UTCEPSS rescore
  5. 2026-08-09 19:10 UTCOSV refresh
  6. 2026-08-08 16:31 UTCEPSS rescore
  7. 2026-08-06 13:41 UTCEPSS rescore
  8. 2026-07-30 16:22 UTCEPSS rescore
  9. 2026-07-26 13:39 UTCEG score recompute▲ 5.00
  10. 2026-07-25 14:12 UTCEPSS rescore
  11. 2026-07-24 20:11 UTCOSV refresh
  12. 2026-07-24 14:12 UTCEPSS rescore
  13. 2026-07-23 14:14 UTCEPSS rescore
  14. 2026-07-23 01:00 UTCEG score recompute
  15. 2026-07-23 00:37 UTCEG score recompute
  16. 2026-07-23 00:04 UTCEG score recompute
  17. 2026-07-22 21:43 UTCEG score recompute
  18. 2026-07-22 14:03 UTCEPSS rescore
  19. 2026-07-21 15:20 UTCEPSS rescore
  20. 2026-07-20 17:03 UTCEPSS rescore
  21. 2026-07-20 17:03 UTCEPSS rescore
  22. 2026-07-18 09:59 UTCEPSS rescore
  23. 2026-07-16 16:58 UTCEPSS rescore
  24. 2026-07-15 16:54 UTCEPSS rescore
  25. 2026-07-15 16:54 UTCEPSS rescore
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  1. 2026-07-15 01:55 UTCEPSS rescore
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  3. 2026-07-13 06:07 UTCEPSS rescore
  4. 2026-07-11 08:22 UTCEPSS rescore
  5. 2026-07-11 08:22 UTCEPSS rescore
  6. 2026-07-09 19:04 UTCEPSS rescore
  7. 2026-07-08 15:10 UTCEPSS rescore
  8. 2026-07-07 15:11 UTCOSV refresh
  9. 2026-07-06 16:23 UTCEPSS rescore
  10. 2026-07-05 02:26 UTCEPSS rescore
  11. 2026-07-05 02:26 UTCEPSS rescore
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  13. 2026-06-30 23:19 UTCEPSS rescore
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  19. 2026-06-27 03:05 UTCEPSS rescore
  20. 2026-06-25 13:46 UTCEPSS rescore
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  22. 2026-06-24 14:02 UTCEPSS rescore
  23. 2026-06-24 14:02 UTCEPSS rescore
  24. 2026-06-23 21:29 UTCEPSS rescore
  25. 2026-06-23 21:29 UTCEPSS rescore
  26. 2026-06-21 01:56 UTCEPSS rescore
  27. 2026-06-21 01:56 UTCEPSS rescore
  28. 2026-06-19 02:35 UTCOSV refresh
  29. 2026-06-18 17:49 UTCEPSS rescore
  30. 2026-06-18 17:49 UTCEPSS rescore
  31. 2026-06-17 17:49 UTCEPSS rescore
  32. 2026-06-17 17:49 UTCEPSS rescore
  33. 2026-06-16 17:49 UTCEPSS rescore
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  35. 2026-06-15 17:44 UTCEPSS rescore
  36. 2026-06-14 23:14 UTCEPSS rescore
  37. 2026-06-14 23:14 UTCEPSS rescore
  38. 2026-06-13 22:57 UTCEPSS rescore
  39. 2026-06-12 23:08 UTCEPSS rescore
  40. 2026-06-12 23:08 UTCEPSS rescore
  41. 2026-06-10 22:14 UTCEPSS rescore
  42. 2026-06-10 13:17 UTCEPSS rescore
  43. 2026-06-08 14:13 UTCEPSS rescore
  44. 2026-06-07 15:22 UTCEPSS rescore
  45. 2026-06-07 15:22 UTCEPSS rescore
  46. 2026-06-05 22:44 UTCEPSS rescore
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  48. 2026-06-05 06:07 UTCEPSS rescore
  49. 2026-06-04 13:09 UTCEPSS rescore
  50. 2026-06-04 13:09 UTCEPSS rescore
  51. 2026-06-02 20:10 UTCEPSS rescore
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  53. 2026-06-01 13:49 UTCEPSS rescore
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  55. 2026-05-31 22:28 UTCEPSS rescore
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  57. 2026-05-31 00:13 UTCEPSS rescore
  58. 2026-05-31 00:13 UTCEPSS rescore
  59. 2026-05-30 14:43 UTCEG score recompute
  60. 2026-05-30 14:43 UTCVendor advisory
  61. 2026-05-30 14:43 UTCGHSA enrichment
  62. 2026-05-29 13:40 UTCEPSS rescore
  63. 2026-05-28 13:42 UTCEPSS rescore
  64. 2026-05-28 13:42 UTCEPSS rescore
  65. 2026-05-28 13:42 UTCEPSS rescore
  66. 2026-05-27 13:38 UTCEPSS rescore
  67. 2026-05-27 13:38 UTCEPSS rescore
  68. 2026-05-26 13:41 UTCEPSS rescore
  69. 2026-05-26 13:41 UTCEPSS rescore
  70. 2026-05-26 07:16 UTCEPSS rescore
  71. 2026-05-26 07:16 UTCEPSS rescore
  72. 2026-05-24 16:43 UTCEPSS rescore
  73. 2026-05-22 21:15 UTCEPSS rescore
  74. 2026-05-22 21:15 UTCEPSS rescore
  75. 2026-05-22 03:06 UTCOSV refresh

Frequently asked(4)

What is CVE-2009-3720?
CVE-2009-3720 is a medium 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 July 20, 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 28% probability of exploitation in the next 30 days, which ranks it in the top 2.1% of all scored CVEs.
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.

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