CVE-2025-6436 - CVE House
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Status published Unknown CVE-2025-6436

Memory safety bugs fixed in Firefox 140 and Thunderbird 140

Vulnerability Description

Memory safety bugs present in Firefox 139 and Thunderbird 139. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 140 and Thunderbird 140.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • Andrew McCreight, Gabriele Svelto, Beth Rennie (she/her), Steven Michaud, the Mozilla Fuzzing Team

References

More from Mozilla

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CVE-2025-9187
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CVE-2025-9185
Memory safety bugs fixed in Firefox ESR 115.27, Firefox ESR 128.14, Thunderbird ESR 128.14, Firefox ESR 140.2, Thunderbird ESR 140.2, Firefox 142 and Thunderbird 142
Unknown 0
CVE-2025-9184
Memory safety bugs fixed in Firefox ESR 140.2, Thunderbird ESR 140.2, Firefox 142 and Thunderbird 142
Unknown 0
CVE-2025-9183
Spoofing issue in the Address Bar component
Unknown 0

Affected Vendor

Affected Software

Firefox, Thunderbird
Vulnerable Versions:
140

Timeline

Official Publish: June 24th, 2025
Last Modified: April 13th, 2026
Added to House: July 22nd, 2026

CVSS Vectors

No vector data available

Weaknesses (CWE)

No CWE data available

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.