CVE-2026-14899

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-22. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 4 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

The code to parse MIME headers for display when forwarding a message (if the setting to view all headers was enabled) had an off-by-one error, allowing a single byte to be read from the memory after the buffer for the headers, and potentially crashing Thunderbird. This vulnerability was fixed in Thunderbird 153 and Thunderbird 140.13.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100CISA SSVC

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
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.3%
EPSS %ILE
17th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

July 22, 2026

Last Modified

August 12, 2026

Advisory Details (3)

Auto-updated Jul 27, 2026
⚠️ Active exploitation confirmed. Patch available.
generic🔴 Active Exploitation

Security Vulnerabilities fixed in Thunderbird 140.13 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-72/
generic

Security Vulnerabilities fixed in Thunderbird 153 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-71/
generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2046137

Vendor Advisories for CVE-2026-14899(11)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(10)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatthunderbird-0:140.13.0-1.el8_42026-08-11redhat
redhatthunderbird-0:140.13.0-1.el8_82026-08-11redhat
redhatthunderbird-0:140.13.0-1.el9_42026-08-11redhat
redhatthunderbird-0:140.13.0-1.el10_02026-08-11redhat
redhatthunderbird-0:140.13.0-1.el8_62026-08-11redhat
redhatthunderbird-0:140.13.0-1.el9_62026-08-11redhat
redhatthunderbird-0:140.13.0-1.el9_22026-08-11redhat
redhatthunderbird-0:140.13.0-1.el8_102026-08-04redhat
redhatthunderbird-0:140.13.0-1.el9_82026-08-04redhat
redhatthunderbird-0:140.13.0-1.el10_22026-08-03redhat

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 rangeFix by version rangeDependents
thunderbird1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (334 versions)
  • every version up to 1:140.13.0esr-1: fixed in 1:140.13.0esr-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
thunderbird1:102.11.0-1 ... 1:140.9.1esr-1~deb13u1 (220 versions)
  • every version up to 1:140.13.0esr-2~deb12u1: fixed in 1:140.13.0esr-2~deb12u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (76 versions)
  • every version up to 1:140.13.0esr-2~deb13u1: fixed in 1:140.13.0esr-2~deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (73 versions)
  • every version up to 1:140.13.0esr-1: fixed in 1:140.13.0esr-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 14× in last 7d / 87× 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 306 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-14899?
CVE-2026-14899 is a high vulnerability published on July 22, 2026. The code to parse MIME headers for display when forwarding a message (if the setting to view all headers was enabled) had an off-by-one error, allowing a single byte to be read from the memory after the buffer for the headers, and potentially crashing Thunderbird. This vulnerability was fixed in…
When was CVE-2026-14899 disclosed?
CVE-2026-14899 was first published on July 22, 2026, with the most recent update on August 12, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-14899 actively exploited?
CVE-2026-14899 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (17th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-14899?
CVE-2026-14899 has a CVSS v3.1 base score of 7.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-14899?
A fix for CVE-2026-14899 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-14899 are linked in the Vendor Advisories panel on this page.

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