Mozilla developers reported memory safety bugs present in Firefox 92 and Firefox ESR 91.1.
Priority MEDIUM 41Published · 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
Mozilla developers reported memory safety bugs present in Firefox 92 and Firefox ESR 91.1. 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 < 78.15, Thunderbird < 91.2, Firefox ESR < 91.2, Firefox ESR < 78.15, and Firefox < 93.
Why it matters now
EPSS 0.01273 70th percentileScored 2026-11-07
Fix Partial Thunderbird (Mozilla): 78.15, 91.2Firefox ESR (Mozilla): 91.2, 78.15+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
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Mozilla | Thunderbird | before 78.15; before 91.2 | 78.15, 91.2 | Patch available | CNA |
| Mozilla | Firefox ESR | before 91.2; before 78.15 | 91.2, 78.15 | Patch available | CNA |
| Mozilla | Firefox | before 93 | 93 | Patch available | CNA |
- Thunderbird VendorMozilla Affected before 78.15; before 91.2 Fixed in 78.15, 91.2 Patch available CNA
- Firefox ESR VendorMozilla Affected before 91.2; before 78.15 Fixed in 91.2, 78.15 Patch available CNA
- Firefox VendorMozilla Affected before 93 Fixed in 93 Patch available CNA
CPE configurations NVD · 6
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* | before 93.0; 91.0 to before 91.2 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* | before 78.15 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* | before 78.15; 91.0 to before 91.2 | 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:firefox:*:*:*:*:*:*:*:* Versions before 93.0; 91.0 to before 91.2 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 78.15 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 78.15; 91.0 to before 91.2 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 78.15, 91.2
- Fix · CNA Firefox ESR (Mozilla) Fixed in 91.2, 78.15
- Fix · CNA Firefox (Mozilla) Fixed in 93
Red Hat 8 advisories
- RHSA-2021:3841 Released 2021-10-13 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux Client (v. 7) thunderbird-91.2.0-1.el7_9
- Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-91.2.0-1.el7_9
- Red Hat Enterprise Linux Workstation (v. 7) thunderbird-91.2.0-1.el7_9
- RHSA-2021:3838 Released 2021-10-13 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream (v. 8) thunderbird-91.2.0-1.el8_4
- RHSA-2021:3839 Released 2021-10-13 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.2) thunderbird-91.2.0-1.el8_2
Show 5 more Red Hat advisories
- RHSA-2021:3840 Released 2021-10-13 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird-91.2.0-1.el8_1
- RHSA-2021:3791 Released 2021-10-12 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux Client (v. 7) firefox-91.2.0-4.el7_9
- Red Hat Enterprise Linux Client Optional (v. 7) firefox-91.2.0-4.el7_9
- Red Hat Enterprise Linux Server (v. 7) firefox-91.2.0-4.el7_9
- Red Hat Enterprise Linux Server Optional (v. 7) firefox-91.2.0-4.el7_9
- Red Hat Enterprise Linux Workstation (v. 7) firefox-91.2.0-4.el7_9
- Red Hat Enterprise Linux Workstation Optional (v. 7) firefox-91.2.0-4.el7_9
- RHSA-2021:3755 Released 2021-10-11 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream (v. 8) firefox-91.2.0-4.el8_4
- RHSA-2021:3757 Released 2021-10-11 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox-91.2.0-4.el8_1
- RHSA-2021:3756 Released 2021-10-11 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.2) firefox-91.2.0-4.el8_2
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
Mozilla Firefox 93
6 records Highest priority Priority MEDIUM 4 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2021-16096 Use after free in Mozilla ThunderbirdPriority MEDIUM 41
- TI-2021-16101 Mozilla developers reported memory safety bugs present in Firefox 92 and Firefox ESR 91.1.Priority MEDIUM 40
- TI-2021-16099 Out-of-bounds write in Mozilla FirefoxPriority MEDIUM 40
- Release ·
Mozilla Firefox ESR, Thunderbird 78.15, 91.2
2 records Highest priority Priority MEDIUM 2 MEDIUM
Other records, highest priority first
- TI-2021-16096 Use after free in Mozilla ThunderbirdPriority MEDIUM 41
Vendor assessments
Red Hat
Red Hat rating: Important. 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-2021:3755, RHSA-2021:3838 |
| Red Hat Enterprise Linux AppStream EUS (v. 8.1) | Fixed | RHSA-2021:3757, RHSA-2021:3840 |
| Red Hat Enterprise Linux AppStream EUS (v. 8.2) | Fixed | RHSA-2021:3756, RHSA-2021:3839 |
| Red Hat Enterprise Linux Client (v. 7) | Fixed | RHSA-2021:3791, RHSA-2021:3841 |
| Red Hat Enterprise Linux Client Optional (v. 7) | Fixed | RHSA-2021:3791 |
| Red Hat Enterprise Linux Server (v. 7) | Fixed | RHSA-2021:3791 |
| Red Hat Enterprise Linux Server Optional (v. 7) | Fixed | RHSA-2021:3791, RHSA-2021:3841 |
| Red Hat Enterprise Linux Workstation (v. 7) | Fixed | RHSA-2021:3791, RHSA-2021:3841 |
| Red Hat Enterprise Linux Workstation Optional (v. 7) | Fixed | RHSA-2021:3791 |
Timeline
- 2026-10-02 Threatist record created from CVE-2021-38500
- 2026-10-03 Alias added: GHSA-pv72-mgh4-jqvg
References
Advisory 7
- https://www.mozilla.org/security/advisories/mfsa2021-47/
- https://www.mozilla.org/security/advisories/mfsa2021-45/
- https://www.mozilla.org/security/advisories/mfsa2021-43/
- https://www.mozilla.org/security/advisories/mfsa2021-46/
- https://www.mozilla.org/security/advisories/mfsa2021-44/
- DSA-5034
- [debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security update
More Mozilla Firefox 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-2021-38500 · CVE Program
- CVE-2021-38500 · NVD
- FIRST EPSS
- GHSA-pv72-mgh4-jqvg · GitHub Advisory Database · CC BY 4.0
- CVE-2021-38500 · Red Hat security data · CC BY 4.0
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