Memory Safety Flaws in Firefox and Thunderbird by Mozilla
CVE-2025-9187

9.8CRITICAL

Key Information:

Vendor

Mozilla
Status
Firefox
Thunderbird
Vendor
CVE Published:
19 August 2025

What is CVE-2025-9187?

Mozilla has identified memory safety bugs in Firefox and Thunderbird, specifically in versions prior to 142. These vulnerabilities indicate potential memory corruption issues, which could be leveraged by attackers to execute arbitrary code through sophisticated exploits. Users of affected versions are strongly urged to update to Firefox and Thunderbird 142 or later to mitigate the risks posed by these flaws.

Affected Version(s)

Firefox < 142

Thunderbird < 142

References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1825621%2...
https://www.mozilla.org/security/advisories/mfsa2025-64/
https://www.mozilla.org/security/advisories/mfsa2025-70/

CVSS V3.1

Score:
9.8
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Andy Leiserson, Maurice Dauer, Sebastian Hengst and the Mozilla Fuzzing Team
.
CVE-2025-9187 : Memory Safety Flaws in Firefox and Thunderbird by Mozilla