Improper privilege management in Mozilla Thunderbird
Priority LOW 31CWE-269Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Privilege escalation
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Partial Red Hat: 7 fixed, 1 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-269.
Summary
Thunderbird unexpectedly enabled JavaScript in the composition area. The JavaScript execution context was limited to this area and did not receive chrome-level privileges, but could be used as a stepping stone to further an attack with other vulnerabilities. This vulnerability affects Thunderbird < 91.4.0.
Why it matters now
EPSS 0.01309 70th percentileScored 2026-11-07
Fix Partial Thunderbird (Mozilla): 91.4.0Red Hat: 5 advisoriesRed Hat: 7 fixed, 1 without a fix
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Mozilla | Thunderbird | before 91.4.0 | 91.4.0 | Patch available | CNA |
- Thunderbird VendorMozilla Affected before 91.4.0 Fixed in 91.4.0 Patch available CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* | before 91.4.0 | Vulnerable | Mozilla |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* | 11.0 | Vulnerable | Debian |
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 91.4.0 Vulnerable ·Mozilla
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* Versions 11.0 Vulnerable ·Debian
Remediation
- Fix · CNA Thunderbird (Mozilla) Fixed in 91.4.0
Red Hat 5 advisories
- RHSA-2021:5055 Released 2021-12-09 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream E4S (v. 8.1) thunderbird-91.4.0-2.el8_1
- RHSA-2021:5046 Released 2021-12-09 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux Client (v. 7) thunderbird-91.4.0-3.el7_9
- Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-91.4.0-3.el7_9
- Red Hat Enterprise Linux Workstation (v. 7) thunderbird-91.4.0-3.el7_9
- RHSA-2021:5048 Released 2021-12-09 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v.8.4) thunderbird-91.4.0-2.el8_4
Show 2 more Red Hat advisories
- RHSA-2021:5045 Released 2021-12-09 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream (v. 8) thunderbird-91.4.0-2.el8_5
- RHSA-2021:5047 Released 2021-12-09 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.2) thunderbird-91.4.0-2.el8_2
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2021:5045 |
| Red Hat Enterprise Linux AppStream E4S (v. 8.1) | Fixed | RHSA-2021:5055 |
| Red Hat Enterprise Linux AppStream EUS (v. 8.2) | Fixed | RHSA-2021:5047 |
| Red Hat Enterprise Linux AppStream EUS (v.8.4) | Fixed | RHSA-2021:5048 |
| Red Hat Enterprise Linux Client (v. 7) | Fixed | RHSA-2021:5046 |
| Red Hat Enterprise Linux Server Optional (v. 7) | Fixed | RHSA-2021:5046 |
| Red Hat Enterprise Linux Workstation (v. 7) | Fixed | RHSA-2021:5046 |
Timeline
- 2026-10-02 Threatist record created from CVE-2021-43528
- 2026-10-03 Alias added: GHSA-q4gq-74cq-85g9
References
More Mozilla Thunderbird vulnerabilities
- 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
Sources
- CVE-2021-43528 · CVE Program
- CVE-2021-43528 · NVD
- FIRST EPSS
- GHSA-q4gq-74cq-85g9 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-43528 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences