CVE-2006-4253

HIGHCVSS v2 · 7.67.6—
EchelonGraph scoreLOW confidence

This CVE was only ever scored under CVSS v2.0. NVD CVSS v2.0 base 7.6 — 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:N/AC:H/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 14.9% 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
Weaponized
7.6EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • Public exploit code is available (Exploit-DB (verified), epss top5pct, public exploit)
CISA-KEV: Not listedEPSS PROB: 15%CVSS v2: 7.6Exploit: Exploit-DB (verified) · epss top5pct · public exploitExposed: 0

A fix is available — apply it.

Concurrency vulnerability in Mozilla Firefox 1.5.0.6 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via multiple Javascript timed events that load a deeply nested XML file, followed by redirecting the browser to another page, which leads to a concurrency failure that causes structures to be freed incorrectly, as demonstrated by (1) ffoxdie and (2) ffoxdie3. NOTE: it has been reported that Netscape 8.1 and K-Meleon 1.0.1 are also affected by ffoxdie. Mozilla confirmed to CVE that ffoxdie and ffoxdie3 trigger the same underlying vulnerability. NOTE: it was later reported that Firefox 2.0 RC2 and 1.5.0.7 are also affected.

CVSS v2.0 (legacy)
7.6HIGHNVD never assigned a CVSS v3 rating to this CVE
EG Score
7.6(low)
EG Risk
65(Track)
EG Risk 65/100SSVC: 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
Severity76% × 45%
Exploitation65% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
15%
EPSS %ILE
96%
KEV
Not listed

Published

August 21, 2006

Last Modified

April 16, 2026

References (134)

Patch Availability(6)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibnss3 (1.5.dfsg+1.5.0.7-ubuntu0.6.06) @ dapper2026-05-31ubuntu
ubuntumozilla-thunderbird-locale-uk (1.5-ubuntu5.10) @ breezy2026-05-31ubuntu
ubuntumozilla-thunderbird (1.5.0.7-0ubuntu0.6.06) @ dapper2026-05-31ubuntu
redhatseamonkey-0:1.0.5-0.1.el42006-09-15redhat
redhatfirefox-0:1.5.0.7-0.1.el42006-09-15redhat
redhatthunderbird-0:1.5.0.7-0.1.el42006-09-15redhat

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

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
thunderbird—1.5.0.7-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
thunderbird—1.5.0.7-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
thunderbird—1.5.0.7-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
thunderbird—1.5.0.7-1—

All Vendor Advisories

(6)

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 3× in last 7d / 5× 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. 2026-09-10 09:23 UTCEPSS rescore
  2. 2026-09-05 15:21 UTCEPSS rescore
  3. 2026-09-04 04:59 UTCEPSS rescore
  4. 2026-08-30 01:14 UTCEPSS rescore
  5. 2026-08-27 11:53 UTCOSV refresh
  6. 2026-08-11 01:31 UTCOSV refresh
  7. 2026-08-08 16:30 UTCEPSS rescore
  8. 2026-08-05 19:11 UTCEPSS rescore
  9. 2026-08-04 15:03 UTCEPSS rescore
  10. 2026-08-03 10:27 UTCEPSS rescore
  11. 2026-07-26 13:29 UTCEG score recompute▲ 7.60
  12. 2026-07-26 01:42 UTCOSV refresh
  13. 2026-07-24 14:11 UTCEPSS rescore
  14. 2026-07-23 00:51 UTCEG score recompute
  15. 2026-07-23 00:30 UTCEG score recompute
  16. 2026-07-22 23:55 UTCEG score recompute
  17. 2026-07-22 21:35 UTCEG score recompute
  18. 2026-07-20 17:02 UTCEPSS rescore
  19. 2026-07-18 09:59 UTCEPSS rescore
  20. 2026-07-16 16:58 UTCEPSS rescore
  21. 2026-07-15 16:53 UTCEPSS rescore
  22. 2026-07-15 01:55 UTCEPSS rescore
  23. 2026-07-13 22:25 UTCEPSS rescore
  24. 2026-07-13 06:07 UTCEPSS rescore
  25. 2026-07-13 06:07 UTCEPSS rescore
Show 62 more
  1. 2026-07-11 08:22 UTCEPSS rescore
  2. 2026-07-09 19:03 UTCEPSS rescore
  3. 2026-07-08 20:09 UTCOSV refresh
  4. 2026-07-08 15:09 UTCEPSS rescore
  5. 2026-07-04 06:26 UTCEPSS rescore
  6. 2026-07-02 14:00 UTCEPSS rescore
  7. 2026-07-01 15:01 UTCEPSS rescore
  8. 2026-06-27 03:04 UTCEPSS rescore
  9. 2026-06-25 13:46 UTCEPSS rescore
  10. 2026-06-24 14:01 UTCEPSS rescore
  11. 2026-06-24 14:01 UTCEPSS rescore
  12. 2026-06-23 21:29 UTCEPSS rescore
  13. 2026-06-23 21:29 UTCEPSS rescore
  14. 2026-06-20 07:42 UTCOSV refresh
  15. 2026-06-19 19:22 UTCEPSS rescore
  16. 2026-06-19 19:22 UTCEPSS rescore
  17. 2026-06-18 17:49 UTCEPSS rescore
  18. 2026-06-18 17:49 UTCEPSS rescore
  19. 2026-06-17 17:49 UTCEPSS rescore
  20. 2026-06-17 17:49 UTCEPSS rescore
  21. 2026-06-16 17:49 UTCEPSS rescore
  22. 2026-06-16 17:49 UTCEPSS rescore
  23. 2026-06-15 17:44 UTCEPSS rescore
  24. 2026-06-14 23:13 UTCEPSS rescore
  25. 2026-06-13 22:56 UTCEPSS rescore
  26. 2026-06-12 23:08 UTCEPSS rescore
  27. 2026-06-11 13:55 UTCEPSS rescore
  28. 2026-06-10 22:14 UTCEPSS rescore
  29. 2026-06-10 13:17 UTCEPSS rescore
  30. 2026-06-06 13:44 UTCEPSS rescore
  31. 2026-06-06 13:44 UTCEPSS rescore
  32. 2026-06-05 22:43 UTCEPSS rescore
  33. 2026-06-05 06:07 UTCEPSS rescore
  34. 2026-06-05 06:07 UTCEPSS rescore
  35. 2026-06-04 13:09 UTCEPSS rescore
  36. 2026-06-04 13:09 UTCEPSS rescore
  37. 2026-06-02 20:10 UTCEPSS rescore
  38. 2026-06-02 20:10 UTCEPSS rescore
  39. 2026-06-01 13:49 UTCEPSS rescore
  40. 2026-06-01 13:49 UTCEPSS rescore
  41. 2026-06-01 13:49 UTCEPSS rescore
  42. 2026-05-31 22:28 UTCEPSS rescore
  43. 2026-05-31 07:09 UTCEG score recompute
  44. 2026-05-31 07:09 UTCVendor advisory
  45. 2026-05-31 07:09 UTCGHSA enrichment
  46. 2026-05-29 13:40 UTCEPSS rescore
  47. 2026-05-28 13:42 UTCEPSS rescore
  48. 2026-05-28 13:42 UTCEPSS rescore
  49. 2026-05-27 13:37 UTCEPSS rescore
  50. 2026-05-27 13:37 UTCEPSS rescore
  51. 2026-05-26 13:41 UTCEPSS rescore
  52. 2026-05-26 13:41 UTCEPSS rescore
  53. 2026-05-24 16:42 UTCEPSS rescore
  54. 2026-05-24 16:42 UTCOSV refresh
  55. 2026-05-22 21:15 UTCEPSS rescore
  56. 2026-05-22 21:15 UTCEPSS rescore
  57. 2026-05-21 22:38 UTCEPSS rescore
  58. 2026-05-20 22:36 UTCEPSS rescore
  59. 2026-05-20 22:36 UTCEPSS rescore
  60. 2026-05-20 11:20 UTCEPSS rescore
  61. 2026-05-20 11:20 UTCEPSS rescore
  62. 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-28380✓ verified
    First seen Aug 12, 2006

    Mozilla Firefox 1.0.x - JavaScript Handler Race Condition Memory Corruption

    Open source ↗

Frequently asked(4)

What is CVE-2006-4253?
CVE-2006-4253 is a high vulnerability published on August 21, 2006. Concurrency vulnerability in Mozilla Firefox 1.5.0.6 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via multiple Javascript timed events that load a deeply nested XML file, followed by redirecting the browser to another page, which leads…
When was CVE-2006-4253 disclosed?
CVE-2006-4253 was first published in the National Vulnerability Database on August 21, 2006, with the most recent update on April 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2006-4253 actively exploited?
CVE-2006-4253 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 15% probability of exploitation in the next 30 days, which ranks it in the top 3.5% of all scored CVEs.
How do I remediate CVE-2006-4253?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2006-4253, 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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