// For flags

CVE-2021-43541

Mozilla: External protocol handler parameters were unescaped

Severity Score

6.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

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.

Cuando son invocados manejadores de protocolo para protocolos externos, una URL de parĂ¡metro suministrada que contenĂ­a espacios no se escapaba correctamente. Esta vulnerabilidad afecta a Thunderbird versiones anteriores a 91.4.0, Firefox ESR versiones anteriores a 91.4.0 y Firefox versiones anteriores a 95

Multiple security issues were discovered in Firefox. If a user were tricked into opening a specially crafted website, an attacker could potentially exploit these to cause a denial of service, obtain sensitive information, conduct spoofing attacks, bypass CSP restrictions, or execute arbitrary code. A security issue was discovered with the handling of WebExtension permissions. If a user were tricked into installing a specially crafted extension, an attacker could potentially exploit this to create and install a service worker that wouldn't be uninstalled with the extension. Various other issues were also addressed.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
Attack Vector
Network
Attack Complexity
Medium
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-11-08 CVE Reserved
  • 2021-12-08 CVE Published
  • 2024-08-04 CVE Updated
  • 2025-04-10 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-428: Unquoted Search Path or Element
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Mozilla
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Firefox
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< 95.0
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-
Affected
Mozilla
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Firefox Esr
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< 91.4.0
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-
Affected
Mozilla
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Thunderbird
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< 91.4.0
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-
Affected
Debian
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Debian Linux
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9.0
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-
Affected
Debian
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Debian Linux
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10.0
Search vendor "Debian" for product "Debian Linux" and version "10.0"
-
Affected
Debian
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Debian Linux
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11.0
Search vendor "Debian" for product "Debian Linux" and version "11.0"
-
Affected