When invoking protocol handlers for external protocols, a supplied parameter URL…
Priority LOW 32Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Partial Red Hat: 10 fixed, 1 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
When invoking protocol handlers for external protocols, a supplied parameter URL containing spaces was not properly escaped. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95.
Why it matters now
EPSS 0.01694 77th percentileScored 2026-11-07
Fix Partial Thunderbird (Mozilla): 91.4.0Firefox ESR (Mozilla): 91.4.0+1 more productRed Hat: 10 advisoriesRed Hat: 10 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 |
| Mozilla | Firefox ESR | before 91.4.0 | 91.4.0 | Patch available | CNA |
| Mozilla | Firefox | before 95 | 95 | Patch available | CNA |
- Thunderbird VendorMozilla Affected before 91.4.0 Fixed in 91.4.0 Patch available CNA
- Firefox ESR VendorMozilla Affected before 91.4.0 Fixed in 91.4.0 Patch available CNA
- Firefox VendorMozilla Affected before 95 Fixed in 95 Patch available CNA
CPE configurations NVD · 6
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* | before 95.0 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* | before 91.4.0 | Vulnerable | Mozilla |
| 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:firefox:*:*:*:*:*:*:*:* Versions before 95.0 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 91.4.0 Vulnerable ·Mozilla
- 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
- Fix · CNA Firefox ESR (Mozilla) Fixed in 91.4.0
- Fix · CNA Firefox (Mozilla) Fixed in 95
Red Hat 10 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 7 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
- RHSA-2021:5014 Released 2021-12-08 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux Client (v. 7) firefox-91.4.0-1.el7_9
- Red Hat Enterprise Linux Client Optional (v. 7) firefox-91.4.0-1.el7_9
- Red Hat Enterprise Linux Server (v. 7) firefox-91.4.0-1.el7_9
- Red Hat Enterprise Linux Server Optional (v. 7) firefox-91.4.0-1.el7_9
- Red Hat Enterprise Linux Workstation (v. 7) firefox-91.4.0-1.el7_9
- Red Hat Enterprise Linux Workstation Optional (v. 7) firefox-91.4.0-1.el7_9
- RHSA-2021:5016 Released 2021-12-08 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.2) firefox-91.4.0-1.el8_2
- RHSA-2021:5015 Released 2021-12-08 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream EUS (v.8.4) firefox-91.4.0-1.el8_4
- RHSA-2021:5013 Released 2021-12-08 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream (v. 8) firefox-91.4.0-1.el8_5
- RHSA-2021:5017 Released 2021-12-08 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream E4S (v. 8.1) firefox-91.4.0-1.el8_1
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
Mozilla Firefox, Firefox ESR, Thunderbird — DSA-5026
17 records Highest priority Priority MEDIUM 6 MEDIUM, 11 LOW
Other records, highest priority first
- TI-2021-16103 Incorrect authorization in Mozilla FirefoxPriority MEDIUM 50
- TI-2021-19429 Use after free in Mozilla ThunderbirdPriority MEDIUM 42
- TI-2021-19427 Incorrect type conversion in Mozilla ThunderbirdPriority MEDIUM 42
Vendor assessments
Red Hat
Red Hat rating: Moderate. 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-2021:5013, RHSA-2021:5045 |
| Red Hat Enterprise Linux AppStream E4S (v. 8.1) | Fixed | RHSA-2021:5017, RHSA-2021:5055 |
| Red Hat Enterprise Linux AppStream EUS (v. 8.2) | Fixed | RHSA-2021:5016, RHSA-2021:5047 |
| Red Hat Enterprise Linux AppStream EUS (v.8.4) | Fixed | RHSA-2021:5015, RHSA-2021:5048 |
| Red Hat Enterprise Linux Client (v. 7) | Fixed | RHSA-2021:5014, RHSA-2021:5046 |
| Red Hat Enterprise Linux Client Optional (v. 7) | Fixed | RHSA-2021:5014 |
| Red Hat Enterprise Linux Server (v. 7) | Fixed | RHSA-2021:5014 |
| Red Hat Enterprise Linux Server Optional (v. 7) | Fixed | RHSA-2021:5014, RHSA-2021:5046 |
| Red Hat Enterprise Linux Workstation (v. 7) | Fixed | RHSA-2021:5014, RHSA-2021:5046 |
| Red Hat Enterprise Linux Workstation Optional (v. 7) | Fixed | RHSA-2021:5014 |
Timeline
- 2026-10-02 Threatist record created from CVE-2021-43541
- 2026-10-03 Alias added: GHSA-33wh-q6g3-v2vg
References
Advisory 10
- https://www.mozilla.org/security/advisories/mfsa2021-53/
- https://www.mozilla.org/security/advisories/mfsa2021-54/
- https://www.mozilla.org/security/advisories/mfsa2021-52/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1696685
- DSA-5026
- [debian-lts-announce] 20211229 [SECURITY] [DLA 2863-1] firefox-esr security update
- DSA-5034
- [debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security update
- GLSA-202202-03
- GLSA-202208-14
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-2021-43541 · CVE Program
- CVE-2021-43541 · NVD
- FIRST EPSS
- GHSA-33wh-q6g3-v2vg · GitHub Advisory Database · CC BY 4.0
- CVE-2021-43541 · Red Hat security data · CC BY 4.0
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