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TI-2021-10606 Aliases CVE-2021-29989GHSA-2j98-m58x-h9xv

Out-of-bounds write in Mozilla Thunderbird

Priority MEDIUM 41CWE-787Published · 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: 9 fixed, 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-787 and the CVSS impact.

Summary

Mozilla developers reported memory safety bugs present in Firefox 90 and Firefox ESR 78.12. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Thunderbird < 78.13, Firefox ESR < 78.13, and Firefox < 91.

Why it matters now

EPSS 0.01268 69th percentileScored 2026-11-07
Fix Partial Thunderbird (Mozilla): 78.13Firefox ESR (Mozilla): 78.13+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
MozillaThunderbirdbefore 78.1378.13Patch availableCNA
MozillaFirefox ESRbefore 78.1378.13Patch availableCNA
MozillaFirefoxbefore 9191Patch availableCNA
  • Thunderbird VendorMozilla Affected before 78.13 Fixed in 78.13 Patch available CNA
  • Firefox ESR VendorMozilla Affected before 78.13 Fixed in 78.13 Patch available CNA
  • Firefox VendorMozilla Affected before 91 Fixed in 91 Patch available CNA

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*before 91.0VulnerableMozilla
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*before 78.13.0VulnerableMozilla
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*before 78.13.0VulnerableMozilla
  • cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 91.0 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 78.13.0 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 78.13.0 Vulnerable ·Mozilla

Remediation

  • Fix · CNA Thunderbird (Mozilla) Fixed in 78.13
  • Fix · CNA Firefox ESR (Mozilla) Fixed in 78.13
  • Fix · CNA Firefox (Mozilla) Fixed in 91

Red Hat 8 advisories

  • RHSA-2021:3160 Released 2021-08-16 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux Client (v. 7) thunderbird-78.13.0-1.el7_9
    • Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-78.13.0-1.el7_9
    • Red Hat Enterprise Linux Workstation (v. 7) thunderbird-78.13.0-1.el7_9
  • RHSA-2021:3157 Released 2021-08-16 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux AppStream (v. 8) firefox-78.13.0-2.el8_4
  • RHSA-2021:3154 Released 2021-08-16 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux Client (v. 7) firefox-78.13.0-2.el7_9
    • Red Hat Enterprise Linux Client Optional (v. 7) firefox-78.13.0-2.el7_9
    • Red Hat Enterprise Linux Server (v. 7) firefox-78.13.0-2.el7_9
    • Red Hat Enterprise Linux Server Optional (v. 7) firefox-78.13.0-2.el7_9
    • Red Hat Enterprise Linux Workstation (v. 7) firefox-78.13.0-2.el7_9
    • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox-78.13.0-2.el7_9
Show 5 more Red Hat advisories
  • RHSA-2021:3155 Released 2021-08-16 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream (v. 8) thunderbird-78.13.0-1.el8_4
  • RHSA-2021:3162 Released 2021-08-16 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.2) thunderbird-78.13.0-1.el8_2
  • RHSA-2021:3156 Released 2021-08-16 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.2) firefox-78.13.0-2.el8_2
  • RHSA-2021:3159 Released 2021-08-16 · Red Hat rating Important
    firefox security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox-78.13.0-2.el8_1
  • RHSA-2021:3161 Released 2021-08-16 · Red Hat rating Important
    thunderbird security update
    • Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird-78.13.0-1.el8_1

Fixed in the same release

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

  • Release ·

    Mozilla Firefox 91

    11 records Highest priority Priority MEDIUM 7 MEDIUM, 4 LOW

    Other records, highest priority first

    • TI-2021-10605 Out-of-bounds read in Mozilla ThunderbirdPriority MEDIUM 41
    • TI-2021-10602 Use after free in Mozilla ThunderbirdPriority MEDIUM 41
    • TI-2021-10601 Out-of-bounds write in Mozilla ThunderbirdPriority MEDIUM 41
    Show all 11 records →
  • Release ·

    Mozilla Firefox ESR 78.13

    6 records Highest priority Priority MEDIUM 5 MEDIUM, 1 LOW

    Other records, highest priority first

    • TI-2021-10605 Out-of-bounds read in Mozilla ThunderbirdPriority MEDIUM 41
    • TI-2021-10602 Use after free in Mozilla ThunderbirdPriority MEDIUM 41
    • TI-2021-10601 Out-of-bounds write in Mozilla ThunderbirdPriority MEDIUM 41
    Show all 6 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-2021:3155, RHSA-2021:3157
Red Hat Enterprise Linux AppStream EUS (v. 8.1)Fixed RHSA-2021:3159, RHSA-2021:3161
Red Hat Enterprise Linux AppStream EUS (v. 8.2)Fixed RHSA-2021:3156, RHSA-2021:3162
Red Hat Enterprise Linux Client (v. 7)Fixed RHSA-2021:3154, RHSA-2021:3160
Red Hat Enterprise Linux Client Optional (v. 7)Fixed RHSA-2021:3154
Red Hat Enterprise Linux Server (v. 7)Fixed RHSA-2021:3154
Red Hat Enterprise Linux Server Optional (v. 7)Fixed RHSA-2021:3154, RHSA-2021:3160
Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2021:3154, RHSA-2021:3160
Red Hat Enterprise Linux Workstation Optional (v. 7)Fixed RHSA-2021:3154

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-29989
  2. 2026-10-03 Alias added: GHSA-2j98-m58x-h9xv

References

Advisory 6

  • 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