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TI-2020-09905 Aliases CVE-2020-12387GHSA-8m69-jh8v-xjx3

Race condition in Mozilla Firefox ESR

Priority LOW 38CWE-362Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 16 fixed, 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.

Summary

A race condition when running shutdown code for Web Worker led to a use-after-free vulnerability. This resulted in a potentially exploitable crash. This vulnerability affects Firefox ESR < 68.8, Firefox < 76, and Thunderbird < 68.8.0.

Why it matters now

EPSS 0.01438 73rd percentileScored 2026-11-07
Fix Partial Firefox ESR (Mozilla): 68.8Firefox (Mozilla): 76+1 more productRed Hat: 10 advisoriesRed Hat: 16 fixed, 1 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
MozillaFirefox ESRbefore 68.868.8Patch availableCNA
MozillaFirefoxbefore 7676Patch availableCNA
MozillaThunderbirdbefore 68.8.068.8.0Patch availableCNA
  • Firefox ESR VendorMozilla Affected before 68.8 Fixed in 68.8 Patch available CNA
  • Firefox VendorMozilla Affected before 76 Fixed in 76 Patch available CNA
  • Thunderbird VendorMozilla Affected before 68.8.0 Fixed in 68.8.0 Patch available CNA

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*before 76.0VulnerableMozilla
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*before 68.8.0VulnerableMozilla
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*before 68.8.0VulnerableMozilla
  • cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 76.0 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 68.8.0 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 68.8.0 Vulnerable ·Mozilla

Remediation

  • Fix · CNA Firefox ESR (Mozilla) Fixed in 68.8
  • Fix · CNA Firefox (Mozilla) Fixed in 76
  • Fix · CNA Thunderbird (Mozilla) Fixed in 68.8.0

Red Hat 10 advisories

  • RHSA-2020:2050 Released 2020-05-11 · Red Hat rating Critical
    thunderbird security update
    • Red Hat Enterprise Linux Client (v. 7) thunderbird-68.8.0-1.el7_8
    • Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-68.8.0-1.el7_8
    • Red Hat Enterprise Linux Workstation (v. 7) thunderbird-68.8.0-1.el7_8
  • RHSA-2020:2049 Released 2020-05-11 · Red Hat rating Critical
    thunderbird security update
    • Red Hat Enterprise Linux Desktop (v. 6) thunderbird-68.8.0-1.el6_10
    • Red Hat Enterprise Linux Server Optional (v. 6) thunderbird-68.8.0-1.el6_10
    • Red Hat Enterprise Linux Workstation (v. 6) thunderbird-68.8.0-1.el6_10
  • RHSA-2020:2046 Released 2020-05-11 · Red Hat rating Critical
    thunderbird security update
    • Red Hat Enterprise Linux AppStream (v. 8) thunderbird-68.8.0-1.el8_2
Show 7 more Red Hat advisories
  • RHSA-2020:2047 Released 2020-05-11 · Red Hat rating Critical
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird-68.8.0-1.el8_1
  • RHSA-2020:2048 Released 2020-05-11 · Red Hat rating Critical
    thunderbird security update
    • Red Hat Enterprise Linux AppStream E4S (v. 8.0) thunderbird-68.8.0-1.el8_0
  • RHSA-2020:2036 Released 2020-05-06 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux Desktop (v. 6) firefox-68.8.0-1.el6_10
    • Red Hat Enterprise Linux Desktop Optional (v. 6) firefox-68.8.0-1.el6_10
    • Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox-68.8.0-1.el6_10
    • Red Hat Enterprise Linux Server (v. 6) firefox-68.8.0-1.el6_10
    • Red Hat Enterprise Linux Server Optional (v. 6) firefox-68.8.0-1.el6_10
    • Red Hat Enterprise Linux Workstation (v. 6) firefox-68.8.0-1.el6_10
    • Red Hat Enterprise Linux Workstation Optional (v. 6) firefox-68.8.0-1.el6_10
  • RHSA-2020:2037 Released 2020-05-06 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux Client (v. 7) firefox-68.8.0-1.el7_8
    • Red Hat Enterprise Linux Client Optional (v. 7) firefox-68.8.0-1.el7_8
    • Red Hat Enterprise Linux Server (v. 7) firefox-68.8.0-1.el7_8
    • Red Hat Enterprise Linux Server Optional (v. 7) firefox-68.8.0-1.el7_8
    • Red Hat Enterprise Linux Workstation (v. 7) firefox-68.8.0-1.el7_8
    • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox-68.8.0-1.el7_8
  • RHSA-2020:2031 Released 2020-05-06 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux AppStream (v. 8) firefox-68.8.0-1.el8_2
  • RHSA-2020:2032 Released 2020-05-06 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox-68.8.0-1.el8_1
  • RHSA-2020:2033 Released 2020-05-06 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux AppStream E4S (v. 8.0) firefox-68.8.0-1.el8_0

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Advisory ·

    Mozilla Firefox, Firefox ESR, Thunderbird — USN-4373-1

    5 records Highest priority Priority MEDIUM 2 MEDIUM, 3 LOW

    Other records, highest priority first

    • TI-2020-05540 Out-of-bounds write in Mozilla Firefox ESRPriority MEDIUM 51
    • TI-2020-09913 Out-of-bounds write in Mozilla Firefox ESRPriority MEDIUM 47
    • TI-2020-09910 Path traversal in Mozilla Firefox ESRPriority LOW 25
    Show all 5 records → Advisory →

Vendor assessments

Red Hat

Red Hat rating: Critical. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 5AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2020:2031, RHSA-2020:2046
Red Hat Enterprise Linux AppStream E4S (v. 8.0)Fixed RHSA-2020:2033, RHSA-2020:2048
Red Hat Enterprise Linux AppStream EUS (v. 8.1)Fixed RHSA-2020:2032, RHSA-2020:2047
Red Hat Enterprise Linux Client (v. 7)Fixed RHSA-2020:2037, RHSA-2020:2050
Red Hat Enterprise Linux Client Optional (v. 7)Fixed RHSA-2020:2037
Red Hat Enterprise Linux Desktop (v. 6)Fixed RHSA-2020:2036, RHSA-2020:2049
Red Hat Enterprise Linux Desktop Optional (v. 6)Fixed RHSA-2020:2036
Red Hat Enterprise Linux HPC Node Optional (v. 6)Fixed RHSA-2020:2036
Red Hat Enterprise Linux Server (v. 6)Fixed RHSA-2020:2036
Red Hat Enterprise Linux Server (v. 7)Fixed RHSA-2020:2037
Red Hat Enterprise Linux Server Optional (v. 6)Fixed RHSA-2020:2036, RHSA-2020:2049
Red Hat Enterprise Linux Server Optional (v. 7)Fixed RHSA-2020:2037, RHSA-2020:2050
Red Hat Enterprise Linux Workstation (v. 6)Fixed RHSA-2020:2036, RHSA-2020:2049
Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2020:2037, RHSA-2020:2050
Red Hat Enterprise Linux Workstation Optional (v. 6)Fixed RHSA-2020:2036
Red Hat Enterprise Linux Workstation Optional (v. 7)Fixed RHSA-2020:2037

Timeline

  1. 2026-10-02 Threatist record created from CVE-2020-12387
  2. 2026-10-03 Alias added: GHSA-8m69-jh8v-xjx3

References

Advisory 6

Other 1

  • TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
  • TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
  • TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
  • TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
  • TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
  • TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
See all 3444 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences