CVE-2020-12420
CVSS v3
8.8
HIGH
EPSS Score
1.9 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
When trying to connect to a STUN server, a race condition could have caused a use-after-free of a pointer, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox ESR < 68.10, Firefox < 78, and Thunderbird < 68.10.0.
Technical details
- Published
- 2020-07-09
Frequently asked questions
What is CVE-2020-12420?
When trying to connect to a STUN server, a race condition could have caused a use-after-free of a pointer, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox ESR < 68.10, Firefox < 78, and Thunderbird < 68.10.0.
Is CVE-2020-12420 actively exploited?
Active exploitation of CVE-2020-12420 has not been confirmed. Its EPSS score was 1.9% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2020-12420?
CVE-2020-12420 has a CVSS v3 base score of 8.8 (HIGH severity).
Is CVE-2020-12420 affecting your environment?
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