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TI-2021-06314 Aliases CVE-2021-23995GHSA-h42x-74c2-hxvc

When Responsive Design Mode was enabled, it used references to objects that were…

Priority MEDIUM 40CWE-672Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 9 fixed, 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

When Responsive Design Mode was enabled, it used references to objects that were previously freed. We presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

Why it matters now

EPSS 0.01181 67th percentileScored 2026-11-07
Fix Partial Firefox ESR (Mozilla): 78.10Thunderbird (Mozilla): 78.10+1 more productRed Hat: 8 advisoriesRed Hat: 9 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 78.1078.10Patch availableCNA
MozillaThunderbirdbefore 78.1078.10Patch availableCNA
MozillaFirefoxbefore 8888Patch availableCNA
  • Firefox ESR VendorMozilla Affected before 78.10 Fixed in 78.10 Patch available CNA
  • Thunderbird VendorMozilla Affected before 78.10 Fixed in 78.10 Patch available CNA
  • Firefox VendorMozilla Affected before 88 Fixed in 88 Patch available CNA

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*before 88.0VulnerableMozilla
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*before 78.10VulnerableMozilla
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*before 78.10VulnerableMozilla
  • cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 88.0 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 78.10 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 78.10 Vulnerable ·Mozilla

Remediation

  • Fix · CNA Firefox ESR (Mozilla) Fixed in 78.10
  • Fix · CNA Thunderbird (Mozilla) Fixed in 78.10
  • Fix · CNA Firefox (Mozilla) Fixed in 88

Red Hat 8 advisories

  • RHSA-2021:1363 Released 2021-04-26 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux Client (v. 7) firefox-78.10.0-1.el7_9
    • Red Hat Enterprise Linux Client Optional (v. 7) firefox-78.10.0-1.el7_9
    • Red Hat Enterprise Linux Server (v. 7) firefox-78.10.0-1.el7_9
    • Red Hat Enterprise Linux Server Optional (v. 7) firefox-78.10.0-1.el7_9
    • Red Hat Enterprise Linux Workstation (v. 7) firefox-78.10.0-1.el7_9
    • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox-78.10.0-1.el7_9
  • RHSA-2021:1361 Released 2021-04-26 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.2) firefox-78.10.0-1.el8_2
  • RHSA-2021:1360 Released 2021-04-26 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux AppStream (v. 8) firefox-78.10.0-1.el8_3
Show 5 more Red Hat advisories
  • RHSA-2021:1362 Released 2021-04-26 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox-78.10.0-1.el8_1
  • RHSA-2021:1350 Released 2021-04-26 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux Client (v. 7) thunderbird-78.10.0-1.el7_9
    • Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-78.10.0-1.el7_9
    • Red Hat Enterprise Linux Workstation (v. 7) thunderbird-78.10.0-1.el7_9
  • RHSA-2021:1352 Released 2021-04-26 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.2) thunderbird-78.10.0-1.el8_2
  • RHSA-2021:1351 Released 2021-04-26 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird-78.10.0-1.el8_1
  • RHSA-2021:1353 Released 2021-04-26 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream (v. 8) thunderbird-78.10.0-1.el8_3

Fixed in the same release

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

  • Release ·

    Mozilla Firefox 88

    13 records Highest priority Priority MEDIUM 7 MEDIUM, 6 LOW

    Other records, highest priority first

    • TI-2021-06313 Missing initialization of resource in Mozilla Firefox ESRPriority MEDIUM 42
    • TI-2021-10563 Integer overflow in Mozilla Firefox ESRPriority MEDIUM 41
    • TI-2021-06318 Improper privilege management in Mozilla Firefox ESRPriority MEDIUM 41
    Show all 13 records →
  • Release ·

    Mozilla Thunderbird 78.10

    8 records Highest priority Priority MEDIUM 5 MEDIUM, 3 LOW

    Other records, highest priority first

    • TI-2021-06313 Missing initialization of resource in Mozilla Firefox ESRPriority MEDIUM 42
    • TI-2021-10563 Integer overflow in Mozilla Firefox ESRPriority MEDIUM 41
    • TI-2021-06318 Improper privilege management in Mozilla Firefox ESRPriority MEDIUM 41
    Show all 8 records →
Show 1 more group
  • Release ·

    Mozilla Firefox ESR 78.10

    7 records Highest priority Priority MEDIUM 5 MEDIUM, 2 LOW

    Other records, highest priority first

    • TI-2021-06313 Missing initialization of resource in Mozilla Firefox ESRPriority MEDIUM 42
    • TI-2021-10563 Integer overflow in Mozilla Firefox ESRPriority MEDIUM 41
    • TI-2021-06318 Improper privilege management in Mozilla Firefox ESRPriority MEDIUM 41
    Show all 7 records →

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2021:1353, RHSA-2021:1360
Red Hat Enterprise Linux AppStream EUS (v. 8.1)Fixed RHSA-2021:1351, RHSA-2021:1362
Red Hat Enterprise Linux AppStream EUS (v. 8.2)Fixed RHSA-2021:1352, RHSA-2021:1361
Red Hat Enterprise Linux Client (v. 7)Fixed RHSA-2021:1350, RHSA-2021:1363
Red Hat Enterprise Linux Client Optional (v. 7)Fixed RHSA-2021:1363
Red Hat Enterprise Linux Server (v. 7)Fixed RHSA-2021:1363
Red Hat Enterprise Linux Server Optional (v. 7)Fixed RHSA-2021:1350, RHSA-2021:1363
Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2021:1350, RHSA-2021:1363
Red Hat Enterprise Linux Workstation Optional (v. 7)Fixed RHSA-2021:1363

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-23995
  2. 2026-10-03 Alias added: GHSA-h42x-74c2-hxvc

References

Advisory 4

  • 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