CVE-1999-0284

NONECVSS 0.0Weaponized
0.0
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No confirmed exploitation signals yet
CISA-KEV: Not listedEPSS: 12%CVSS: —Exploit: NoneExposed: 0

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

Denial of service to NT mail servers including Ipswitch, Mdaemon, and Exchange through a buffer overflow in the SMTP HELO command.

CVSS v3
—
EG Score
0.0(none)
EPSS
95.6%
KEV
Not listed

Published

January 1, 1998

Last Modified

June 16, 2026

References (2)

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 4× in last 7d / 15× 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. 2026-07-22 21:24 UTCEG score recompute
  2. 2026-07-20 17:02 UTCEPSS rescore
  3. 2026-07-18 09:59 UTCEPSS rescore
  4. 2026-07-16 16:58 UTCEPSS rescore
  5. 2026-07-15 16:53 UTCEPSS rescore
  6. 2026-07-15 01:55 UTCEPSS rescore
  7. 2026-07-13 06:07 UTCEPSS rescore
  8. 2026-07-11 08:22 UTCEPSS rescore
  9. 2026-07-08 15:08 UTCEPSS rescore
  10. 2026-07-02 14:00 UTCEPSS rescore
  11. 2026-06-29 14:02 UTCEPSS rescore
  12. 2026-06-28 14:02 UTCEPSS rescore
  13. 2026-06-27 03:04 UTCEPSS rescore
  14. 2026-06-24 14:01 UTCEPSS rescore
  15. 2026-06-23 21:29 UTCEPSS rescore
  16. 2026-06-22 14:22 UTCEPSS rescore
  17. 2026-06-21 01:56 UTCEPSS rescore
  18. 2026-06-19 19:22 UTCEPSS rescore
  19. 2026-06-18 17:49 UTCEPSS rescore
  20. 2026-06-18 17:49 UTCEPSS rescore
  21. 2026-06-17 17:49 UTCEPSS rescore
  22. 2026-06-16 17:49 UTCEPSS rescore
  23. 2026-06-14 23:13 UTCEPSS rescore
  24. 2026-06-13 22:56 UTCEPSS rescore
  25. 2026-06-12 23:07 UTCEPSS rescore
Show 33 more
  1. 2026-06-11 13:55 UTCEPSS rescore
  2. 2026-06-10 22:13 UTCEPSS rescore
  3. 2026-06-10 13:17 UTCEPSS rescore
  4. 2026-06-07 15:21 UTCEPSS rescore
  5. 2026-06-06 13:44 UTCEPSS rescore
  6. 2026-06-05 06:07 UTCEPSS rescore
  7. 2026-06-04 13:09 UTCEPSS rescore
  8. 2026-06-02 20:10 UTCEPSS rescore
  9. 2026-05-31 22:57 UTCEG score recompute
  10. 2026-05-31 22:57 UTCGHSA enrichment
  11. 2026-05-31 22:27 UTCEPSS rescore
  12. 2026-05-31 00:13 UTCEPSS rescore
  13. 2026-05-31 00:13 UTCEPSS rescore
  14. 2026-05-29 13:40 UTCEPSS rescore
  15. 2026-05-28 13:42 UTCEPSS rescore
  16. 2026-05-28 13:42 UTCEPSS rescore
  17. 2026-05-28 13:42 UTCEPSS rescore
  18. 2026-05-28 13:42 UTCEPSS rescore
  19. 2026-05-27 13:37 UTCEPSS rescore
  20. 2026-05-27 13:37 UTCEPSS rescore
  21. 2026-05-26 13:41 UTCEPSS rescore
  22. 2026-05-26 13:41 UTCEPSS rescore
  23. 2026-05-26 13:41 UTCEPSS rescore
  24. 2026-05-26 07:16 UTCEPSS rescore
  25. 2026-05-26 07:16 UTCEPSS rescore
  26. 2026-05-24 16:42 UTCEPSS rescore
  27. 2026-05-22 21:15 UTCEPSS rescore
  28. 2026-05-21 22:38 UTCEPSS rescore
  29. 2026-05-20 22:36 UTCEPSS rescore
  30. 2026-05-20 11:20 UTCEPSS rescore
  31. 2026-05-20 11:20 UTCEPSS rescore
  32. 2026-05-18 21:29 UTCEPSS rescore
  33. 2026-05-18 21:29 UTCEPSS rescore

Publicly available exploits

(3 references)

Working exploit code is in the public domain (3 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-23146✓ verified
    First seen Mar 10, 1999

    Alt-N MDaemon Server 2.71 SP1 - SMTP HELO Argument Buffer Overflow

    Open source ↗
  • Exploit-DBEDB-23145✓ verified
    First seen Mar 10, 1998

    Ipswitch Imail Server 5.0 - SMTP HELO Argument Buffer Overflow

    Open source ↗
  • Exploit-DBEDB-23113✓ verified
    First seen Mar 10, 1998

    Microsoft Exchange Server 4.0/5.0 - SMTP HELO Argument Buffer Overflow

    Open source ↗

Frequently asked(4)

What is CVE-1999-0284?
CVE-1999-0284 is a none vulnerability published on January 1, 1998. Denial of service to NT mail servers including Ipswitch, Mdaemon, and Exchange through a buffer overflow in the SMTP HELO command.
When was CVE-1999-0284 disclosed?
CVE-1999-0284 was first published in the National Vulnerability Database on January 1, 1998, 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-1999-0284 actively exploited?
CVE-1999-0284 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 95.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
How do I remediate CVE-1999-0284?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-1999-0284, 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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