CVE-2003-0866

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 32.7% 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
Weaponized
5.0EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 33%CVSS v2: 5.0Exploit: Exploit-DB (verified) · epss top5pct · public exploitExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

The Catalina org.apache.catalina.connector.http package in Tomcat 4.0.x up to 4.0.3 allows remote attackers to cause a denial of service via several requests that do not follow the HTTP protocol, which causes Tomcat to reject later requests.

CVSS v2.0 (legacy)
5.0MEDIUMNVD never assigned a CVSS v3 rating to this CVE
EG Score
5.0(low)
EG Risk
53(Track)
EG Risk 53/100SSVC: 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%
Exploitation65% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
33%
EPSS %ILE
98%
KEV
Not listed

Published

November 17, 2003

Last Modified

June 16, 2026

References (24)

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFixed inDependents
org.apache.tomcat:tomcat—4.1.0—

Data Freshness Timeline

(refreshed 8× in last 7d / 22× 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.

  1. 2026-07-26 13:23 UTCEG score recompute▲ 5.00
  2. 2026-07-25 14:11 UTCEPSS rescore
  3. 2026-07-24 14:11 UTCEPSS rescore
  4. 2026-07-23 00:45 UTCEG score recompute
  5. 2026-07-23 00:26 UTCEG score recompute▼ 0.40
  6. 2026-07-22 23:49 UTCEG score recompute▲ 0.40
  7. 2026-07-22 21:30 UTCEG score recompute
  8. 2026-07-20 17:02 UTCEPSS rescore
  9. 2026-07-19 14:25 UTCEPSS rescore
  10. 2026-07-18 09:59 UTCEPSS rescore
  11. 2026-07-18 09:59 UTCEPSS rescore
  12. 2026-07-16 16:58 UTCEPSS rescore
  13. 2026-07-13 06:07 UTCEPSS rescore
  14. 2026-07-11 08:22 UTCEPSS rescore
  15. 2026-07-11 08:22 UTCEPSS rescore
  16. 2026-07-08 15:09 UTCEPSS rescore
  17. 2026-07-04 06:26 UTCEPSS rescore
  18. 2026-07-02 14:00 UTCEPSS rescore
  19. 2026-06-29 14:02 UTCEPSS rescore
  20. 2026-06-29 14:02 UTCEPSS rescore
  21. 2026-06-28 14:02 UTCEPSS rescore
  22. 2026-06-28 04:52 UTCEPSS rescore
  23. 2026-06-27 03:04 UTCEPSS rescore
  24. 2026-06-23 21:29 UTCEPSS rescore
  25. 2026-06-21 14:52 UTCEPSS rescore
Show 44 more
  1. 2026-06-21 01:56 UTCEPSS rescore
  2. 2026-06-18 17:49 UTCEPSS rescore
  3. 2026-06-18 17:49 UTCEPSS rescore
  4. 2026-06-17 17:49 UTCEPSS rescore
  5. 2026-06-17 17:49 UTCEPSS rescore
  6. 2026-06-16 17:49 UTCEPSS rescore
  7. 2026-06-16 17:49 UTCEPSS rescore
  8. 2026-06-15 17:43 UTCEPSS rescore
  9. 2026-06-14 23:13 UTCEPSS rescore
  10. 2026-06-14 23:13 UTCEPSS rescore
  11. 2026-06-13 22:56 UTCEPSS rescore
  12. 2026-06-12 23:08 UTCEPSS rescore
  13. 2026-06-11 13:55 UTCEPSS rescore
  14. 2026-06-10 22:13 UTCEPSS rescore
  15. 2026-06-10 13:17 UTCEPSS rescore
  16. 2026-06-07 15:21 UTCEPSS rescore
  17. 2026-06-06 13:44 UTCEPSS rescore
  18. 2026-06-06 13:44 UTCEPSS rescore
  19. 2026-06-06 13:44 UTCEPSS rescore
  20. 2026-06-05 22:43 UTCEPSS rescore
  21. 2026-06-05 22:43 UTCEPSS rescore
  22. 2026-06-04 13:09 UTCEPSS rescore
  23. 2026-06-02 20:10 UTCEPSS rescore
  24. 2026-06-01 13:49 UTCEPSS rescore
  25. 2026-06-01 13:49 UTCEPSS rescore
  26. 2026-05-31 22:28 UTCEPSS rescore
  27. 2026-05-31 17:08 UTCEG score recompute
  28. 2026-05-31 00:13 UTCEPSS rescore
  29. 2026-05-31 00:13 UTCEPSS rescore
  30. 2026-05-29 13:40 UTCEPSS rescore
  31. 2026-05-29 13:40 UTCEPSS rescore
  32. 2026-05-28 13:42 UTCEPSS rescore
  33. 2026-05-28 13:42 UTCEPSS rescore
  34. 2026-05-28 13:42 UTCEPSS rescore
  35. 2026-05-27 13:37 UTCEPSS rescore
  36. 2026-05-26 07:16 UTCEPSS rescore
  37. 2026-05-26 07:16 UTCEPSS rescore
  38. 2026-05-24 16:42 UTCEPSS rescore
  39. 2026-05-22 21:15 UTCEPSS rescore
  40. 2026-05-20 22:36 UTCEPSS rescore
  41. 2026-05-20 11:20 UTCEPSS rescore
  42. 2026-05-20 11:20 UTCEPSS rescore
  43. 2026-05-18 21:29 UTCEPSS rescore
  44. 2026-05-18 21:29 UTCEPSS rescore

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-23245✓ verified
    First seen Oct 15, 2003

    Apache Tomcat 4.0.x - Non-HTTP Request Denial of Service

    Open source ↗

Frequently asked(4)

What is CVE-2003-0866?
CVE-2003-0866 is a medium vulnerability published on November 17, 2003. The Catalina org.apache.catalina.connector.http package in Tomcat 4.0.x up to 4.0.3 allows remote attackers to cause a denial of service via several requests that do not follow the HTTP protocol, which causes Tomcat to reject later requests.
When was CVE-2003-0866 disclosed?
CVE-2003-0866 was first published in the National Vulnerability Database on November 17, 2003, with the most recent update on June 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2003-0866 actively exploited?
CVE-2003-0866 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 33% probability of exploitation in the next 30 days, which ranks it in the top 1.8% of all scored CVEs.
How do I remediate CVE-2003-0866?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2003-0866, 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

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