CVE-2026-74989

Internally found bugs fixed in Firefox 154

Published Aug 18, 2026 CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed
Description
Internally found bugs present in Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Description Internally found bugs present in Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154. Internally found bugs present in Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154.
Title Internally found bugs fixed in Thunderbird 154 Internally found bugs fixed in Firefox 154
Type Values Removed Values Added
Description Internally found bugs present in Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154. Internally found bugs present in Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154.
Title Internally found bugs fixed in Firefox 154 Internally found bugs fixed in Thunderbird 154
Type Values Removed Values Added
Description Internally found bugs present in Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154. Internally found bugs present in Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154.
Title Internally found bugs fixed in Thunderbird 154 Internally found bugs fixed in Firefox 154
Type Values Removed Values Added
First Time appeared Mozilla thunderbird
CPEs cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
Vendors & Products Mozilla thunderbird
Type Values Removed Values Added
Weaknesses CWE-119
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-125
CWE-787
Type Values Removed Values Added
Description Internally found bugs present in Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154. Internally found bugs present in Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154.
Title Internally found bugs fixed in Firefox 154 Internally found bugs fixed in Thunderbird 154
References
Type Values Removed Values Added
Weaknesses CWE-125
CWE-787
Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox
Vendors & Products Mozilla
Mozilla firefox
Type Values Removed Values Added
Description Internally found bugs present in Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154.
Title Internally found bugs fixed in Firefox 154
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
mozilla
Published
Updated
Oct 28, 2026, 4:36 PM
Reserved
Aug 17, 2026, 11:59 AM
Status
Modified
Published
Aug 18, 2026, 1:17 PM
Modified
Oct 28, 2026, 5:18 PM
Severity
Moderate
Public date
Aug 18, 2026, 12:23 PM