CVE-2020-12420: Race Condition
Last updated 25 August 2025
Other sources
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.
— Mozilla
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 68.10 - Upgrade
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Thunderbirdto a version that resolves this vulnerability.Fixed in 78 - Upgrade
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Firefoxto a version that resolves this vulnerability.Fixed in 78 - Upgrade
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Firefox ESRto a version that resolves this vulnerability.Fixed in 68.10 - Upgrade
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debian/firefoxto a version that resolves this vulnerability.Fixed in 149.0.2-1 - Upgrade
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debian/firefox-esrto a version that resolves this vulnerability.Fixed in 115.14.0esr-1~deb11u1Fixed in 140.9.1esr-1~deb11u1Fixed in 128.14.0esr-1~deb12u1Fixed in 140.9.1esr-1~deb12u1Fixed in 140.8.0esr-1~deb13u1Fixed in 140.9.1esr-1~deb13u1Fixed in 140.9.1esr-1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:115.12.0-1~deb11u1Fixed in 1:140.9.1esr-1~deb11u1Fixed in 1:140.6.0esr-1~deb12u1Fixed in 1:140.9.1esr-1~deb12u1Fixed in 1:140.8.0esr-1~deb13u1Fixed in 1:140.9.1esr-1~deb13u1Fixed in 1:140.9.0esr-1Fixed in 1:140.9.1esr-1 - Upgrade
Upgrade
alpine/firefoxto a version that resolves this vulnerability.Fixed in 78.0-r0 - Upgrade
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alpine/firefox-esrto a version that resolves this vulnerability.Fixed in 68.10.0-r0 - Upgrade
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alpine/librewolfto a version that resolves this vulnerability.Fixed in 78.0-r0 - Upgrade
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alpine/mozjs68to a version that resolves this vulnerability.Fixed in 68.10.0-r0 - Upgrade
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alpine/thunderbirdto a version that resolves this vulnerability.Fixed in 68.10.0-r0 - Upgrade
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Thunderbirdto a version that resolves this vulnerability.Fixed in 68.10.0
Event History
Parent advisories
This vulnerability appears in the following advisories.
Peer vulnerabilities
Found alongside the following vulnerabilities.
Frequently Asked Questions
What is CVE-2020-12420?
CVE-2020-12420 is a vulnerability related to a race condition when trying to connect to a STUN server, leading to memory corruption and a potentially exploitable crash.
How does CVE-2020-12420 impact Mozilla Firefox and Thunderbird?
CVE-2020-12420 affects Mozilla Firefox versions up to 78, Mozilla Thunderbird versions up to 78, Mozilla Firefox ESR versions up to 68.10, and Mozilla Thunderbird versions up to 68.10.
What is the severity of CVE-2020-12420?
CVE-2020-12420 has a severity rating of 7 out of 10, indicating a high severity.
How can the CVE-2020-12420 vulnerability be exploited?
The CVE-2020-12420 vulnerability can potentially be exploited by causing a use-after-free of a pointer, leading to memory corruption and a crash.
Where can I find more information about CVE-2020-12420?
More information about CVE-2020-12420 can be found on the Mozilla bugzilla page and the Mozilla security advisories page.