CVE-1999-0040

HIGHCVSS v2 · 7.27.2—
EchelonGraph scoreLOW confidence

This CVE was only ever scored under CVSS v2.0. NVD CVSS v2.0 base 7.2 — v2 rates that HIGH (v2 bands: LOW 0.0–3.9 / MEDIUM 4.0–6.9 / HIGH 7.0–10.0; v2 has no CRITICAL band). Vector AV:L/AC:L/Au:N/C:C/I:C/A:C. 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 1.2% 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
7.2EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • Public exploit code is available (Exploit-DB (verified), public exploit)
CISA-KEV: Not listedEPSS PROB: 1%CVSS v2: 7.2Exploit: Exploit-DB (verified) · public exploitExposed: 0

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

Buffer overflow in Xt library of X Windowing System allows local users to execute commands with root privileges.

CVSS v2.0 (legacy)
7.2HIGHNVD never assigned a CVSS v3 rating to this CVE
EG Score
7.2(low)
EG Risk
63(Track)
EG Risk 63/100SSVC: 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
Severity72% × 45%
Exploitation65% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
66%
KEV
Not listed

Published

May 1, 1997

Last Modified

June 16, 2026

References (2)

Data Freshness Timeline

(refreshed 5× in last 7d / 17× 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 13:18 UTCEG score recompute▲ 7.20
  2. 2026-07-23 00:40 UTCEG score recompute
  3. 2026-07-23 00:22 UTCEG score recompute
  4. 2026-07-22 23:45 UTCEG score recompute
  5. 2026-07-22 21:24 UTCEG score recompute
  6. 2026-07-20 17:02 UTCEPSS rescore
  7. 2026-07-18 09:59 UTCEPSS rescore
  8. 2026-07-16 16:58 UTCEPSS rescore
  9. 2026-07-15 16:53 UTCEPSS rescore
  10. 2026-07-15 01:55 UTCEPSS rescore
  11. 2026-07-13 06:07 UTCEPSS rescore
  12. 2026-07-11 08:22 UTCEPSS rescore
  13. 2026-07-08 15:08 UTCEPSS rescore
  14. 2026-07-04 06:26 UTCEPSS rescore
  15. 2026-07-02 14:00 UTCEPSS rescore
  16. 2026-06-29 14:02 UTCEPSS rescore
  17. 2026-06-28 14:02 UTCEPSS rescore
  18. 2026-06-27 03:04 UTCEPSS rescore
  19. 2026-06-24 14:01 UTCEPSS rescore
  20. 2026-06-23 21:29 UTCEPSS rescore
  21. 2026-06-22 14:22 UTCEPSS rescore
  22. 2026-06-21 01:56 UTCEPSS rescore
  23. 2026-06-19 19:22 UTCEPSS rescore
  24. 2026-06-18 17:49 UTCEPSS rescore
  25. 2026-06-18 17:49 UTCEPSS rescore
Show 39 more
  1. 2026-06-17 17:49 UTCEPSS rescore
  2. 2026-06-16 17:49 UTCEPSS rescore
  3. 2026-06-14 23:13 UTCEPSS rescore
  4. 2026-06-13 22:56 UTCEPSS rescore
  5. 2026-06-12 23:07 UTCEPSS rescore
  6. 2026-06-11 13:55 UTCEPSS rescore
  7. 2026-06-10 22:13 UTCEPSS rescore
  8. 2026-06-10 13:17 UTCEPSS rescore
  9. 2026-06-08 14:13 UTCEPSS rescore
  10. 2026-06-07 15:21 UTCEPSS rescore
  11. 2026-06-06 13:44 UTCEPSS rescore
  12. 2026-06-05 06:07 UTCEPSS rescore
  13. 2026-06-02 20:10 UTCEPSS rescore
  14. 2026-06-01 13:48 UTCEPSS rescore
  15. 2026-05-31 23:05 UTCEG score recompute
  16. 2026-05-31 23:05 UTCGHSA enrichment
  17. 2026-05-31 22:27 UTCEPSS rescore
  18. 2026-05-31 00:13 UTCEPSS rescore
  19. 2026-05-31 00:13 UTCEPSS rescore
  20. 2026-05-29 13:40 UTCEPSS rescore
  21. 2026-05-28 13:42 UTCEPSS rescore
  22. 2026-05-28 13:42 UTCEPSS rescore
  23. 2026-05-28 13:42 UTCEPSS rescore
  24. 2026-05-28 13:42 UTCEPSS rescore
  25. 2026-05-27 13:37 UTCEPSS rescore
  26. 2026-05-27 13:37 UTCEPSS rescore
  27. 2026-05-26 13:41 UTCEPSS rescore
  28. 2026-05-26 13:41 UTCEPSS rescore
  29. 2026-05-26 13:41 UTCEPSS rescore
  30. 2026-05-26 07:16 UTCEPSS rescore
  31. 2026-05-26 07:16 UTCEPSS rescore
  32. 2026-05-24 16:42 UTCEPSS rescore
  33. 2026-05-22 21:15 UTCEPSS rescore
  34. 2026-05-21 22:38 UTCEPSS rescore
  35. 2026-05-20 22:36 UTCEPSS rescore
  36. 2026-05-20 11:20 UTCEPSS rescore
  37. 2026-05-20 11:20 UTCEPSS rescore
  38. 2026-05-18 21:29 UTCEPSS rescore
  39. 2026-05-18 21:29 UTCEPSS rescore

Publicly available exploits

(5 references)

Working exploit code is in the public domain (5 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-19200✓ verified
    First seen Aug 25, 1997

    BSD/OS 2.1 / Caldera UnixWare 7/7.1.0 / FreeBSD 1.1.5.1/2.0 / HP HP-UX 10.34 / IBM AIX 4.2 / SGI IRIX 6.3 / SunOS 4.1.4 - 'libXt Library' Local Overflow / Local Privilege Escalation (1)

    Open source ↗
  • Exploit-DBEDB-19201✓ verified
    First seen Aug 25, 1997

    BSD/OS 2.1 / Caldera UnixWare 7/7.1.0 / FreeBSD 1.1.5.1/2.0 / HP HP-UX 10.34 / IBM AIX 4.2 / SGI IRIX 6.3 / SunOS 4.1.4 - 'libXt Library' Local Overflow / Local Privilege Escalation (2)

    Open source ↗
  • Exploit-DBEDB-19202✓ verified
    First seen Aug 25, 1997

    BSD/OS 2.1 / Caldera UnixWare 7/7.1.0 / FreeBSD 1.1.5.1/2.0 / HP HP-UX 10.34 / IBM AIX 4.2 / SGI IRIX 6.3 / SunOS 4.1.4 - 'libXt Library' Local Overflow / Local Privilege Escalation (3)

    Open source ↗
  • Exploit-DBEDB-331✓ verified
    First seen May 14, 1997

    LibXt - 'XtAppInitialize()' Local Overflow *xterm

    Open source ↗
  • Exploit-DBEDB-322✓ verified
    First seen Aug 24, 1996

    Xt Library - Local Privilege Escalation

    Open source ↗

Frequently asked(4)

What is CVE-1999-0040?
CVE-1999-0040 is a high vulnerability published on May 1, 1997. Buffer overflow in Xt library of X Windowing System allows local users to execute commands with root privileges.
When was CVE-1999-0040 disclosed?
CVE-1999-0040 was first published in the National Vulnerability Database on May 1, 1997, 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-1999-0040 actively exploited?
CVE-1999-0040 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 34.2% of all scored CVEs.
How do I remediate CVE-1999-0040?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-1999-0040, 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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