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TI-2020-16373 Aliases CVE-2020-26950GHSA-cp22-2989-32j9

Use after free in Mozilla Firefox

Priority HIGH 66CWE-416Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 15 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

In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable use-after-free condition. This vulnerability affects Firefox < 82.0.3, Firefox ESR < 78.4.1, and Thunderbird < 78.4.2.

Why it matters now

EPSS 0.42327 98th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix Partial Firefox (Mozilla): 82.0.3Firefox ESR (Mozilla): 78.4.1+1 more productRed Hat: 12 advisoriesRed Hat: 15 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
MozillaFirefoxbefore 82.0.382.0.3Patch availableCNA
MozillaFirefox ESRbefore 78.4.178.4.1Patch availableCNA
MozillaThunderbirdbefore 78.4.278.4.2Patch availableCNA
  • Firefox VendorMozilla Affected before 82.0.3 Fixed in 82.0.3 Patch available CNA
  • Firefox ESR VendorMozilla Affected before 78.4.1 Fixed in 78.4.1 Patch available CNA
  • Thunderbird VendorMozilla Affected before 78.4.2 Fixed in 78.4.2 Patch available CNA

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*before 82.0.3VulnerableMozilla
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*before 78.4.1VulnerableMozilla
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*before 78.4.2VulnerableMozilla
  • cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 82.0.3 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 78.4.1 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 78.4.2 Vulnerable ·Mozilla

Remediation

  • Fix · CNA Firefox (Mozilla) Fixed in 82.0.3
  • Fix · CNA Firefox ESR (Mozilla) Fixed in 78.4.1
  • Fix · CNA Thunderbird (Mozilla) Fixed in 78.4.2

Red Hat 12 advisories

  • RHSA-2020:5163 Released 2020-11-23 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux Client (v. 7) thunderbird-78.4.3-1.el7_9
    • Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-78.4.3-1.el7_9
    • Red Hat Enterprise Linux Workstation (v. 7) thunderbird-78.4.3-1.el7_9
  • RHSA-2020:5164 Released 2020-11-23 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux Desktop (v. 6) thunderbird-78.4.3-1.el6_10
    • Red Hat Enterprise Linux Server Optional (v. 6) thunderbird-78.4.3-1.el6_10
    • Red Hat Enterprise Linux Workstation (v. 6) thunderbird-78.4.3-1.el6_10
  • RHSA-2020:5162 Released 2020-11-23 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.2) thunderbird-78.4.3-1.el8_2
Show 9 more Red Hat advisories
  • RHSA-2020:5166 Released 2020-11-23 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird-78.4.3-1.el8_1
  • RHSA-2020:5167 Released 2020-11-23 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream E4S (v. 8.0) thunderbird-78.4.3-1.el8_0
  • RHSA-2020:5146 Released 2020-11-18 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream (v. 8) thunderbird-78.4.3-1.el8_3
  • RHSA-2020:5138 Released 2020-11-17 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux AppStream E4S (v. 8.0) firefox-78.4.1-1.el8_0
  • RHSA-2020:5135 Released 2020-11-17 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox-78.4.1-1.el8_1
  • RHSA-2020:5139 Released 2020-11-17 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.2) firefox-78.4.1-1.el8_2
  • RHSA-2020:5099 Released 2020-11-12 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux Client (v. 7) firefox-78.4.1-1.el7_9
    • Red Hat Enterprise Linux Client Optional (v. 7) firefox-78.4.1-1.el7_9
    • Red Hat Enterprise Linux Server (v. 7) firefox-78.4.1-1.el7_9
    • Red Hat Enterprise Linux Server Optional (v. 7) firefox-78.4.1-1.el7_9
    • Red Hat Enterprise Linux Workstation (v. 7) firefox-78.4.1-1.el7_9
    • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox-78.4.1-1.el7_9
  • RHSA-2020:5104 Released 2020-11-12 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux Desktop (v. 6) firefox-78.4.1-1.el6_10
    • Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox-78.4.1-1.el6_10
    • Red Hat Enterprise Linux Server (v. 6) firefox-78.4.1-1.el6_10
    • Red Hat Enterprise Linux Workstation (v. 6) firefox-78.4.1-1.el6_10
  • RHSA-2020:5100 Released 2020-11-12 · Red Hat rating Critical
    firefox security update
    • Red Hat Enterprise Linux AppStream (v. 8) firefox-78.4.1-1.el8_3

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-2020:5100, RHSA-2020:5146
Red Hat Enterprise Linux AppStream E4S (v. 8.0)Fixed RHSA-2020:5138, RHSA-2020:5167
Red Hat Enterprise Linux AppStream EUS (v. 8.1)Fixed RHSA-2020:5135, RHSA-2020:5166
Red Hat Enterprise Linux AppStream EUS (v. 8.2)Fixed RHSA-2020:5139, RHSA-2020:5162
Red Hat Enterprise Linux Client (v. 7)Fixed RHSA-2020:5099, RHSA-2020:5163
Red Hat Enterprise Linux Client Optional (v. 7)Fixed RHSA-2020:5099
Red Hat Enterprise Linux Desktop (v. 6)Fixed RHSA-2020:5104, RHSA-2020:5164
Red Hat Enterprise Linux HPC Node Optional (v. 6)Fixed RHSA-2020:5104
Red Hat Enterprise Linux Server (v. 6)Fixed RHSA-2020:5104
Red Hat Enterprise Linux Server (v. 7)Fixed RHSA-2020:5099
Red Hat Enterprise Linux Server Optional (v. 6)Fixed RHSA-2020:5164
Red Hat Enterprise Linux Server Optional (v. 7)Fixed RHSA-2020:5099, RHSA-2020:5163
Red Hat Enterprise Linux Workstation (v. 6)Fixed RHSA-2020:5104, RHSA-2020:5164
Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2020:5099, RHSA-2020:5163
Red Hat Enterprise Linux Workstation Optional (v. 7)Fixed RHSA-2020:5099

Timeline

  1. 2026-10-02 Threatist record created from CVE-2020-26950
  2. 2026-10-03 Alias added: GHSA-cp22-2989-32j9

References

Exploit 2

Advisory 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