vulnerability
Debian: CVE-2021-23995: firefox-esr, thunderbird -- security update
| Severity | CVSS | Published | Added | Modified |
|---|---|---|---|---|
| 5 | (AV:N/AC:H/Au:N/C:P/I:P/A:P) | Apr 23, 2021 | Apr 23, 2021 | Mar 30, 2026 |
Severity
5
CVSS
(AV:N/AC:H/Au:N/C:P/I:P/A:P)
Published
Apr 23, 2021
Added
Apr 23, 2021
Modified
Mar 30, 2026
Description
When Responsive Design Mode was enabled, it used references to objects that were previously freed. We presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.
Solutions
debian-upgrade-firefox-esrdebian-upgrade-thunderbird
Rapid7 Labs
2026 Global Threat Landscape Report
The predictive window has collapsed. Exploitation follows disclosure in days. See how attackers are accelerating and how to stay ahead.