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TI-2026-71686 Aliases CVE-2026-109780GHSA-h533-hm9m-8rqf

Mitigation bypass in Mozilla Firefox and Thunderbird DOM component

Priority MEDIUM 49CWE-693Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-693.

Summary

Mozilla Firefox and Thunderbird are affected. A protection mechanism failure in the DOM: Core & HTML component allows a mitigation bypass (CWE-693). An unauthenticated remote attacker can bypass security protections without user interaction, with high impact to confidentiality, integrity and availability.

Written with Claude Haiku 5.5 from the sources below · 2026-10-31

Description from the CNA

Mitigation bypass in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 158 and Thunderbird 158.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00363 30th percentileScored 2026-11-07
Fix Fixed Firefox (Mozilla): 158Thunderbird (Mozilla): 158

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

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

Affected products

VendorProductAffected versionsFixed inStatusSource
MozillaFirefox—158Patch availableCNA
MozillaThunderbird—158Patch availableCNA
  • Firefox VendorMozilla Affected — Fixed in 158 Patch available CNA
  • Thunderbird VendorMozilla Affected — Fixed in 158 Patch available CNA

CPE names Threatist (inferred) · 2

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*——Mozilla
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*——Mozilla
  • cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions — — ·Mozilla
  • cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions — — ·Mozilla

Remediation

Mozilla Firefox should be updated to version 158. Mozilla Thunderbird should be updated to version 158.

Written with Claude Haiku 5.5 from the sources below · 2026-10-31

  • Fix · CNA Firefox (Mozilla) Fixed in 158
  • Fix · CNA Thunderbird (Mozilla) Fixed in 158

Vendor assessments

Red Hat

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

Not affected: 5 products
  • Red Hat Enterprise Linux 10
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-13 Threatist record created from CVE-2026-109780
  2. 2026-10-13 Alias added: GHSA-h533-hm9m-8rqf
  3. 2026-10-13 Fix available: Mozilla/Thunderbird@158 · CNA
  4. 2026-10-13 1 new reference · CNA
  5. 2026-10-26 CVSS score added · CISA ADP
  6. 2026-10-26 Weakness changed · CISA ADP
  7. 2026-10-26 CISA SSVC decision points changed
  8. 2026-10-26 Priority changed: LOW → MEDIUM
  9. 2026-10-31 Affected versions changed · Red Hat
  10. 2026-10-31 CVSS score added · Red Hat

References

Other 3

  • 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 4204 →

Sources

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