It was possible to construct specific XSLT markup that would be able to bypass an iframe sandbox. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-2880-1 firefox-esr security update
Debian DLA Debian DLA DLA-2881-1 thunderbird security update
Debian DSA Debian DSA DSA-5044-1 firefox-esr security update
Debian DSA Debian DSA DSA-5045-1 thunderbird security update
EUVD EUVD EUVD-2021-34009 It was possible to construct specific XSLT markup that would be able to bypass an iframe sandbox. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.
Ubuntu USN Ubuntu USN USN-5229-1 Firefox vulnerabilities
Ubuntu USN Ubuntu USN USN-5246-1 Thunderbird vulnerabilities
Ubuntu USN Ubuntu USN USN-5248-1 Thunderbird vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 16 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00051}

epss

{'score': 0.00053}


Wed, 16 Apr 2025 16:15:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 10.0, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2025-04-16T15:55:20.960Z

Reserved: 2021-12-20T00:00:00.000Z

Link: CVE-2021-4140

cve-icon Vulnrichment

Updated: 2024-08-03T17:16:04.229Z

cve-icon NVD

Status : Modified

Published: 2022-12-22T20:15:12.250

Modified: 2025-04-16T16:15:19.117

Link: CVE-2021-4140

cve-icon Redhat

Severity : Important

Publid Date: 2022-01-11T00:00:00Z

Links: CVE-2021-4140 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses