CVE-2009-0021

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:P/I:N/A:N. 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 3.1% 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
5.0EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 3%CVSS v2: 5.0Exploit: None knownExposed: 0

A fix is available — apply it.

NTP 4.2.4 before 4.2.4p5 and 4.2.5 before 4.2.5p150 does not properly check the return value from the OpenSSL EVP_VerifyFinal function, which allows remote attackers to bypass validation of the certificate chain via a malformed SSL/TLS signature for DSA and ECDSA keys, a similar vulnerability to CVE-2008-5077.

CVSS v2.0 (legacy)
5.0MEDIUMNVD never assigned a CVSS v3 rating to this CVE
EG Score
5.0(low)
EG Risk
28(Track)
EG Risk 28/100SSVC: 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%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
3%
EPSS %ILE
87%
KEV
Not listed

Published

January 7, 2009

Last Modified

April 23, 2026

References (38)

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuntp (1:4.2.4p4+dfsg-6ubuntu2.2) @ intrepid2026-05-30ubuntu
redhatntp-0:4.2.2p1-9.el5_3.12009-01-29redhat

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

(2 across 2 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
ntp—1:4.2.4p4+dfsg-8—
Debian:4.0(1)
PackageVulnerable rangeFixed inDependents
ntp1:4.2.2.p4+dfsg-21:4.2.2.p4+dfsg-2etch1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(2)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 2× in last 7d / 11× 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 116 total refreshes for this CVE.

  1. 2026-08-26 13:02 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. 2026-08-10 01:40 UTCOSV refresh
  6. 2026-08-09 13:41 UTCEPSS rescore
  7. 2026-08-08 16:31 UTCEPSS rescore
  8. 2026-08-06 13:41 UTCEPSS rescore
  9. 2026-08-03 10:28 UTCEPSS rescore
  10. 2026-07-30 16:22 UTCEPSS rescore
  11. 2026-07-30 01:26 UTCEPSS rescore
  12. 2026-07-26 13:37 UTCEG score recompute▲ 5.00
  13. 2026-07-25 14:12 UTCEPSS rescore
  14. 2026-07-25 02:41 UTCOSV refresh
  15. 2026-07-24 14:12 UTCEPSS rescore
  16. 2026-07-23 14:14 UTCEPSS rescore
  17. 2026-07-23 00:58 UTCEG score recompute
  18. 2026-07-23 00:36 UTCEG score recompute
  19. 2026-07-23 00:03 UTCEG score recompute
  20. 2026-07-22 21:42 UTCEG score recompute
  21. 2026-07-22 14:03 UTCEPSS rescore
  22. 2026-07-21 15:20 UTCEPSS rescore
  23. 2026-07-20 17:03 UTCEPSS rescore
  24. 2026-07-20 17:03 UTCEPSS rescore
  25. 2026-07-18 09:59 UTCEPSS rescore
Show 75 more
  1. 2026-07-16 16:58 UTCEPSS rescore
  2. 2026-07-15 16:54 UTCEPSS rescore
  3. 2026-07-15 16:54 UTCEPSS rescore
  4. 2026-07-15 01:55 UTCEPSS rescore
  5. 2026-07-13 22:25 UTCEPSS rescore
  6. 2026-07-13 06:07 UTCEPSS rescore
  7. 2026-07-11 08:22 UTCEPSS rescore
  8. 2026-07-11 08:22 UTCEPSS rescore
  9. 2026-07-09 19:04 UTCEPSS rescore
  10. 2026-07-08 15:10 UTCEPSS rescore
  11. 2026-07-07 21:27 UTCOSV refresh
  12. 2026-07-06 16:23 UTCEPSS rescore
  13. 2026-07-06 02:19 UTCEPSS rescore
  14. 2026-07-06 02:19 UTCEPSS rescore
  15. 2026-07-05 02:26 UTCEPSS rescore
  16. 2026-07-05 02:26 UTCEPSS rescore
  17. 2026-07-04 06:27 UTCEPSS rescore
  18. 2026-07-01 15:02 UTCEPSS rescore
  19. 2026-06-30 23:19 UTCEPSS rescore
  20. 2026-06-28 04:52 UTCEPSS rescore
  21. 2026-06-28 04:52 UTCEPSS rescore
  22. 2026-06-27 03:05 UTCEPSS rescore
  23. 2026-06-25 13:46 UTCEPSS rescore
  24. 2026-06-25 13:46 UTCEPSS rescore
  25. 2026-06-24 14:02 UTCEPSS rescore
  26. 2026-06-24 14:02 UTCEPSS rescore
  27. 2026-06-23 21:29 UTCEPSS rescore
  28. 2026-06-23 21:29 UTCEPSS rescore
  29. 2026-06-22 14:22 UTCEPSS rescore
  30. 2026-06-22 14:22 UTCEPSS rescore
  31. 2026-06-21 14:53 UTCEPSS rescore
  32. 2026-06-21 01:56 UTCEPSS rescore
  33. 2026-06-21 01:56 UTCEPSS rescore
  34. 2026-06-19 19:22 UTCEPSS rescore
  35. 2026-06-19 19:22 UTCEPSS rescore
  36. 2026-06-19 09:25 UTCOSV refresh
  37. 2026-06-18 17:49 UTCEPSS rescore
  38. 2026-06-18 17:49 UTCEPSS rescore
  39. 2026-06-17 17:49 UTCEPSS rescore
  40. 2026-06-17 17:49 UTCEPSS rescore
  41. 2026-06-16 17:49 UTCEPSS rescore
  42. 2026-06-16 17:49 UTCEPSS rescore
  43. 2026-06-15 17:44 UTCEPSS rescore
  44. 2026-06-14 23:14 UTCEPSS rescore
  45. 2026-06-14 23:14 UTCEPSS rescore
  46. 2026-06-13 22:57 UTCEPSS rescore
  47. 2026-06-12 23:08 UTCEPSS rescore
  48. 2026-06-12 23:08 UTCEPSS rescore
  49. 2026-06-10 22:14 UTCEPSS rescore
  50. 2026-06-10 13:17 UTCEPSS rescore
  51. 2026-06-08 14:13 UTCEPSS rescore
  52. 2026-06-07 15:22 UTCEPSS rescore
  53. 2026-06-07 15:22 UTCEPSS rescore
  54. 2026-06-06 13:44 UTCEPSS rescore
  55. 2026-06-06 13:44 UTCEPSS rescore
  56. 2026-06-06 13:44 UTCEPSS rescore
  57. 2026-06-05 22:44 UTCEPSS rescore
  58. 2026-06-05 22:44 UTCEPSS rescore
  59. 2026-06-05 06:07 UTCEPSS rescore
  60. 2026-06-04 13:09 UTCEPSS rescore
  61. 2026-06-04 13:09 UTCEPSS rescore
  62. 2026-06-02 20:10 UTCEPSS rescore
  63. 2026-06-02 20:10 UTCEPSS rescore
  64. 2026-06-01 13:49 UTCEPSS rescore
  65. 2026-06-01 13:49 UTCEPSS rescore
  66. 2026-05-31 22:28 UTCEPSS rescore
  67. 2026-05-31 22:28 UTCEPSS rescore
  68. 2026-05-31 00:13 UTCEPSS rescore
  69. 2026-05-31 00:13 UTCEPSS rescore
  70. 2026-05-30 18:51 UTCEG score recompute
  71. 2026-05-30 18:51 UTCVendor advisory
  72. 2026-05-30 18:51 UTCGHSA enrichment
  73. 2026-05-29 13:40 UTCEPSS rescore
  74. 2026-05-28 13:42 UTCEPSS rescore
  75. 2026-05-28 13:42 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(4)

What is CVE-2009-0021?
CVE-2009-0021 is a medium vulnerability published on January 7, 2009. NTP 4.2.4 before 4.2.4p5 and 4.2.5 before 4.2.5p150 does not properly check the return value from the OpenSSL EVP_VerifyFinal function, which allows remote attackers to bypass validation of the certificate chain via a malformed SSL/TLS signature for DSA and ECDSA keys, a similar vulnerability to…
When was CVE-2009-0021 disclosed?
CVE-2009-0021 was first published in the National Vulnerability Database on January 7, 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-2009-0021 actively exploited?
CVE-2009-0021 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3% probability of exploitation in the next 30 days, which ranks it in the top 12.7% of all scored CVEs.
How do I remediate CVE-2009-0021?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2009-0021, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2009-0021

Explore →

Is Your Infrastructure Affected by CVE-2009-0021?

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

Start Free Scan →Browse All CVEs