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TI-2026-58182 Aliases CVE-2026-84640GHSA-2q8r-2ghc-82v8

One byte overflow read in mail parser

Priority LOW 38CWE-126Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
High · None · None
Fix status
Partial Red Hat: 13 fixed, 3 without a fix

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-126 and the CVSS impact.

Summary

A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00263 18th percentileScored 2026-11-07
Fix Partial Thunderbird (Mozilla): 140.15, 153.2, 155Red Hat: 10 advisoriesRed Hat: 13 fixed, 3 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MozillaThunderbird—140.15, 153.2, 155Patch availableCNA
  • Thunderbird VendorMozilla Affected — Fixed in 140.15, 153.2, 155 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*before 140.15.0; 141.0 to before 153.2.0; 154.0 to before 155.0VulnerableMozilla
  • cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 140.15.0; 141.0 to before 153.2.0; 154.0 to before 155.0 Vulnerable ·Mozilla

Remediation

  • Fix · CNA Thunderbird (Mozilla) Fixed in 140.15, 153.2, 155

Red Hat 10 advisories

  • RHSA-2026:82122 Released 2026-10-13 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream AUS (v.8.4) thunderbird-140.16.0-1.el8_4
    • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) thunderbird-140.16.0-1.el8_4
  • RHSA-2026:81912 Released 2026-10-13 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream E4S (v.8.8) thunderbird-140.16.0-1.el8_8
    • Red Hat Enterprise Linux AppStream TUS (v.8.8) thunderbird-140.16.0-1.el8_8
  • RHSA-2026:81913 Released 2026-10-13 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream AUS (v.8.6) thunderbird-140.16.0-1.el8_6
    • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) thunderbird-140.16.0-1.el8_6
Show 7 more Red Hat advisories
  • RHSA-2026:80503 Released 2026-10-12 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v.9.6) thunderbird-140.15.0-1.el9_6
  • RHSA-2026:77632 Released 2026-10-08 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream E4S (v.9.2) thunderbird-140.15.0-1.el9_2
  • RHSA-2026:77627 Released 2026-10-08 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream E4S (v.9.4) thunderbird-140.15.0-1.el9_4
  • RHSA-2026:77631 Released 2026-10-08 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 10.0) thunderbird-140.15.0-1.el10_0
  • RHSA-2026:73971 Released 2026-09-30 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream (v. 8) thunderbird-140.16.0-1.el8_10
  • RHSA-2026:73130 Released 2026-09-29 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream (v. 10) thunderbird-140.16.0-1.el10_2
  • RHSA-2026:70642 Released 2026-09-24 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream (v. 9) thunderbird-140.16.0-1.el9_8

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 10AffectedNo fix yet
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:73130
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2026:73971
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:70642
Red Hat Enterprise Linux AppStream AUS (v.8.4)Fixed RHSA-2026:82122
Red Hat Enterprise Linux AppStream AUS (v.8.6)Fixed RHSA-2026:81913
Red Hat Enterprise Linux AppStream E4S (v.8.8)Fixed RHSA-2026:81912
Red Hat Enterprise Linux AppStream E4S (v.9.2)Fixed RHSA-2026:77632
Red Hat Enterprise Linux AppStream E4S (v.9.4)Fixed RHSA-2026:77627
Red Hat Enterprise Linux AppStream EUS (v. 10.0)Fixed RHSA-2026:77631
Red Hat Enterprise Linux AppStream EUS (v.9.6)Fixed RHSA-2026:80503
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)Fixed RHSA-2026:82122
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6)Fixed RHSA-2026:81913
Red Hat Enterprise Linux AppStream TUS (v.8.8)Fixed RHSA-2026:81912

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-84640
  2. 2026-10-03 Alias added: GHSA-2q8r-2ghc-82v8
  3. 2026-10-08 Fix available: Red Hat Enterprise Linux AppStream E4S (v.9.2), Red Hat Enterprise Linux AppStream E4S (v.9.4), Red Hat Enterprise Linux AppStream EUS (v. 10.0) · Red Hat
  4. 2026-10-09 Fix available: RHSA-2026:77631 · Red Hat
  5. 2026-10-09 Fix available: RHSA-2026:77627 · Red Hat
  6. 2026-10-09 Fix available: RHSA-2026:77632 · Red Hat
  7. 2026-10-12 Fix available: RHSA-2026:80503 · Red Hat
  8. 2026-10-12 Fix available: Red Hat Enterprise Linux AppStream EUS (v.9.6) · Red Hat
  9. 2026-10-13 Fix available: RHSA-2026:81912 · Red Hat
  10. 2026-10-13 Fix available: RHSA-2026:81913 · Red Hat
  11. 2026-10-13 Fix available: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream E4S (v.8.8) +3 · Red Hat
  12. 2026-10-14 Fix available: RHSA-2026:82122 · Red Hat

References

Advisory 3

Other 1

  • TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
  • TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
  • TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
  • TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
  • TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
  • TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
See all 2067 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences