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TI-2021-06303 Aliases CVE-2021-23982GHSA-hg4f-qgj6-3h4w

Using techniques that built on the slipstream research, a malicious webpage could have…

Priority LOW 30CWE-326Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
None · High · None
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. Impact type from CWE-326.

Summary

Using techniques that built on the slipstream research, a malicious webpage could have scanned both an internal network's hosts as well as services running on the user's local machine utilizing WebRTC connections. This vulnerability affects Firefox ESR < 78.9, Firefox < 87, and Thunderbird < 78.9.

Why it matters now

EPSS 0.00743 54th percentileScored 2026-11-07
Fix Partial Firefox ESR (Mozilla): 78.9Firefox (Mozilla): 87+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 78.978.9Patch availableCNA
MozillaFirefoxbefore 8787Patch availableCNA
MozillaThunderbirdbefore 78.978.9Patch availableCNA
  • Firefox ESR VendorMozilla Affected before 78.9 Fixed in 78.9 Patch available CNA
  • Firefox VendorMozilla Affected before 87 Fixed in 87 Patch available CNA
  • Thunderbird VendorMozilla Affected before 78.9 Fixed in 78.9 Patch available CNA

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*before 87.0VulnerableMozilla
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*before 78.9VulnerableMozilla
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*before 78.9VulnerableMozilla
  • cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 87.0 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 78.9 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 78.9 Vulnerable ·Mozilla

Remediation

  • Fix · CNA Firefox ESR (Mozilla) Fixed in 78.9
  • Fix · CNA Firefox (Mozilla) Fixed in 87
  • Fix · CNA Thunderbird (Mozilla) Fixed in 78.9

Red Hat 8 advisories

  • RHSA-2021:0992 Released 2021-03-25 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux Client (v. 7) firefox-78.9.0-1.el7_9
    • Red Hat Enterprise Linux Client Optional (v. 7) firefox-78.9.0-1.el7_9
    • Red Hat Enterprise Linux Server (v. 7) firefox-78.9.0-1.el7_9
    • Red Hat Enterprise Linux Server Optional (v. 7) firefox-78.9.0-1.el7_9
    • Red Hat Enterprise Linux Workstation (v. 7) firefox-78.9.0-1.el7_9
    • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox-78.9.0-1.el7_9
  • RHSA-2021:0996 Released 2021-03-25 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux Client (v. 7) thunderbird-78.9.0-3.el7_9
    • Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-78.9.0-3.el7_9
    • Red Hat Enterprise Linux Workstation (v. 7) thunderbird-78.9.0-3.el7_9
  • RHSA-2021:0994 Released 2021-03-25 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.2) thunderbird-78.9.0-3.el8_2
Show 5 more Red Hat advisories
  • RHSA-2021:0989 Released 2021-03-25 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.2) firefox-78.9.0-1.el8_2
  • RHSA-2021:0993 Released 2021-03-25 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream (v. 8) thunderbird-78.9.0-3.el8_3
  • RHSA-2021:0995 Released 2021-03-25 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird-78.9.0-3.el8_1
  • RHSA-2021:0991 Released 2021-03-25 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox-78.9.0-1.el8_1
  • RHSA-2021:0990 Released 2021-03-25 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux AppStream (v. 8) firefox-78.9.0-1.el8_3

Fixed in the same release

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

  • Release ·

    Mozilla Firefox 87

    8 records Highest priority Priority MEDIUM 2 MEDIUM, 6 LOW

    Other records, highest priority first

    • TI-2021-06308 Out-of-bounds write in Mozilla Firefox ESRPriority MEDIUM 41
    • TI-2021-06309 Out-of-bounds write in Mozilla FirefoxPriority MEDIUM 40
    • TI-2021-06302 Out-of-bounds write in Mozilla Firefox ESRPriority LOW 38
    Show all 8 records →
  • Release ·

    Mozilla Firefox ESR, Thunderbird 78.9

    4 records Highest priority Priority MEDIUM 1 MEDIUM, 3 LOW

    Other records, highest priority first

    • TI-2021-06308 Out-of-bounds write in Mozilla Firefox ESRPriority MEDIUM 41
    • TI-2021-06302 Out-of-bounds write in Mozilla Firefox ESRPriority LOW 38
    • TI-2021-06305 Authentication bypass by spoofing in Mozilla Firefox ESRPriority LOW 31
    Show all 4 records →

Vendor assessments

Red Hat

Red Hat rating: Moderate. 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-2021:0990, RHSA-2021:0993
Red Hat Enterprise Linux AppStream EUS (v. 8.1)Fixed RHSA-2021:0991, RHSA-2021:0995
Red Hat Enterprise Linux AppStream EUS (v. 8.2)Fixed RHSA-2021:0989, RHSA-2021:0994
Red Hat Enterprise Linux Client (v. 7)Fixed RHSA-2021:0992, RHSA-2021:0996
Red Hat Enterprise Linux Client Optional (v. 7)Fixed RHSA-2021:0992
Red Hat Enterprise Linux Server (v. 7)Fixed RHSA-2021:0992
Red Hat Enterprise Linux Server Optional (v. 7)Fixed RHSA-2021:0992, RHSA-2021:0996
Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2021:0992, RHSA-2021:0996
Red Hat Enterprise Linux Workstation Optional (v. 7)Fixed RHSA-2021:0992

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-23982
  2. 2026-10-03 Alias added: GHSA-hg4f-qgj6-3h4w

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