Firefox and Thunderbird: Memory Safety Bugs Can Crash or Run Malicious Code

Summary

Memory safety bugs in Firefox and Thunderbird can cause crashes or allow hackers to run unauthorized code. This affects older versions of Firefox and Thunderbird, which means those users are at risk. To stay safe, update to the latest version of your browser or email client.

What to do

No fix is available yet. Check with your software vendor for updates.

Affected software

Vendor	Product	Affected versions	Fix available
mozilla	firefox	<= 115.33.0	–
mozilla	firefox	<= 148.0	–
mozilla	firefox	> 128.0 , <= 140.8.0	–
mozilla	thunderbird	<= 140.8.0	–
mozilla	thunderbird	<= 148.0	–

Original title

Memory safety bugs present in Firefox ESR 115.32, Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147 and Thunderbird 147. Some of these bugs showed evidence of memory corruption and we presume t...

Original description

Memory safety bugs present in Firefox ESR 115.32, Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147 and Thunderbird 147. 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 affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.

nvd CVSS3.1 9.8

Vulnerability type

CWE-787 Out-of-bounds Write

https://bugzilla.mozilla.org/buglist.cgi?bug_id=2015196%2C2016423%2C2016498 Broken Link
https://www.mozilla.org/security/advisories/mfsa2026-13/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-14/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-15/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-16/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-17/ Vendor Advisory