CVE-2025-0243: Memory safety bugs fixed in Firefox 134, Thunderbird 134, Firefox ESR 128.6, and Thunderbird 128.6
Last updated 9 January 2025
Other sources
Memory safety bugs present in Firefox 133, Thunderbird 133, Firefox ESR 128.5, and Thunderbird 128.5. 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.
— Mozilla
Affected Software
Event History
Parent advisories
This vulnerability appears in the following advisories.
Peer vulnerabilities
Found alongside the following vulnerabilities.
Frequently Asked Questions
What is the severity of CVE-2025-0243?
CVE-2025-0243 is considered a critical vulnerability due to the potential for memory corruption and arbitrary code execution.
How do I fix CVE-2025-0243?
To fix CVE-2025-0243, update to Firefox version 134.0-1 or Thunderbird version 134, depending on the affected application.
Which versions of Firefox are affected by CVE-2025-0243?
CVE-2025-0243 affects Firefox versions 133 and below.
Which versions of Thunderbird are affected by CVE-2025-0243?
CVE-2025-0243 affects Thunderbird versions 133 and below.
Is there a patch available for CVE-2025-0243?
Yes, patches are available in the form of updated software versions for Firefox and Thunderbird.