CVE-2021-23965

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-02-26 · updated 2026-06-17
Weakness: CWE-787

Description

Mozilla developers reported memory safety bugs present in Firefox 84. 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 < 85.

Affected products

Mozilla Firefox: before 85.0 — fixed in 85.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 85.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1670378%2C1673555%2C1676812%2C1678582%2C1684497
https://www.mozilla.org/security/advisories/mfsa2021-03/
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1670378%2C1673555%2C1676812%2C1678582%2C1684497
https://www.mozilla.org/security/advisories/mfsa2021-03/

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