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TI-2021-10605 Aliases CVE-2021-29988GHSA-rqrh-6wcg-wqw7

Out-of-bounds read in Mozilla Thunderbird

Priority MEDIUM 41CWE-125Published · 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

Firefox incorrectly treated an inline list-item element as a block element, resulting in an out of bounds read or memory corruption, and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.13, Thunderbird < 91, Firefox ESR < 78.13, and Firefox < 91.

Why it matters now

EPSS 0.0138 72nd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial Thunderbird (Mozilla): 78.13, 91Firefox 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 78.13; before 9178.13, 91Patch availableCNA
MozillaFirefox ESRbefore 78.1378.13Patch availableCNA
MozillaFirefoxbefore 9191Patch availableCNA
  • Thunderbird VendorMozilla Affected before 78.13; before 91 Fixed in 78.13, 91 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, 91
  • 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-2021-10606 Out-of-bounds write 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-2021-10606 Out-of-bounds write 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 →
Show 1 more group
  • Release ·

    Mozilla Thunderbird 78.13, 91

    5 records Highest priority Priority MEDIUM 4 MEDIUM, 1 LOW

    Other records, highest priority first

    • TI-2021-10602 Use after free in Mozilla ThunderbirdPriority MEDIUM 41
    • TI-2021-10601 Out-of-bounds write in Mozilla ThunderbirdPriority MEDIUM 41
    • TI-2021-10597 Missing initialization of resource in Mozilla ThunderbirdPriority MEDIUM 41
    Show all 5 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-2021-29988
  2. 2026-10-03 Alias added: GHSA-rqrh-6wcg-wqw7

References

Exploit 1

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