CVE-2025-1020

Description

Memory safety bugs present in Firefox 134 and Thunderbird 134. 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 < 135 and Thunderbird < 135.

Category

9.8
CVSS
Severity: Critical
CVSS 3.1 •
EPSS 0.13%
Vendor Advisory mozilla.org Vendor Advisory mozilla.org
Affected: Mozilla Firefox
Affected: Mozilla Thunderbird
Published at:
Updated at:

References

Link Tags
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1939063%2C1942169 broken link
https://www.mozilla.org/security/advisories/mfsa2025-07/ vendor advisory
https://www.mozilla.org/security/advisories/mfsa2025-11/ vendor advisory

Frequently Asked Questions

What is the severity of CVE-2025-1020?
CVE-2025-1020 has been scored as a critical severity vulnerability.
How to fix CVE-2025-1020?
To fix CVE-2025-1020, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2025-1020 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-1020 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-1020?
CVE-2025-1020 affects Mozilla Firefox, Mozilla Thunderbird.
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