Skip to main content
No exploitation reportedFix available

CVE-2020-12420

No exploitation reported by the sources we read.

  • Published2020-07-09
  • WeaknessCWE-362 · CWE-416

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2020-07-0915:15CVE publishedNVD

Versions per branch

NVD
Canonical ubuntu linux
BranchAffectedFixed in
16.4= 16.04no fix published
18.4= 18.04no fix published
19.10= 19.10no fix published
20.4= 20.04no fix published
Opensuse leap
BranchAffectedFixed in
15.1= 15.1no fix published
15.2= 15.2no fix published
Mozilla firefox
BranchAffectedFixed in
78.0< 78.078.0

2 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • firefoxUbuntu:20.04:LTSall versions · fixed in 78.0.1+build1-0ubuntu0.20.04.1
  • firefoxUbuntu:18.04:LTSall versions · fixed in 78.0.1+build1-0ubuntu0.18.04.1
  • firefoxUbuntu:16.04:LTSall versions · fixed in 78.0.1+build1-0ubuntu0.16.04.1
  • firefoxRed Hat:rhel_eus:8.1::appstreamall versions · fixed in 0:68.10.0-1.el8_1and 5 other packages
  • firefoxRed Hat:rhel_e4s:8.0::appstreamall versions · fixed in 0:68.10.0-1.el8_0and 5 other packages
  • firefoxRed Hat:enterprise_linux:8::appstreamall versions · fixed in 0:68.10.0-1.el8_2and 5 other packages
  • firefoxRed Hat:enterprise_linux:7::workstationall versions · fixed in 0:68.10.0-1.el7_8and 3 other packages
  • firefoxRed Hat:enterprise_linux:7::serverall versions · fixed in 0:68.10.0-1.el7_8and 3 other packages

102 more package ranges on OSV.dev

Vendor advisories

  • CVE-2020-12420 Red Hat Product Security138 products fixed · 2 known affected

    Mozilla: Use-After-Free when trying to connect to a STUN server

    firefox.src as a component of Red Hat Enterprise Linux 5 · thunderbird.src as a component of Red Hat Enterprise Linux 5

  • RHSA-2020:3038 Red Hat Product Security10 products fixed

    Red Hat Security Advisory: thunderbird security update

  • RHSA-2020:3046 Red Hat Product Security7 products fixed

    Red Hat Security Advisory: thunderbird security update

  • RHSA-2020:2966 Red Hat Product Security19 products fixed

    Red Hat Security Advisory: thunderbird security update

  • RHSA-2020:2906 Red Hat Product Security11 products fixed

    Red Hat Security Advisory: thunderbird security update

  • RHSA-2020:2907 Red Hat Product Security7 products fixed

    Red Hat Security Advisory: thunderbird security update

5 more advisories

Full record on NVD

Fix

  1. Vendor fix Red Hat Product Security RHSA-2020:3038 · 10 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
  2. Vendor fix Red Hat Product Security RHSA-2020:2827 · 21 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing the update, Firefox must be restarted for the changes to take effect.

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published
2020-07-09
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-g65h-q52v-q3xv

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 2026-11-08, 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), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

Running Mozilla? Hear about its next vulnerability

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

Get alerts for this productCISA KEV additions, November 2026Search CVEs

No credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database

Sources for this record