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.

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation poc

Automatable yes

Technical Impact total

Affected Vendors & Products

Vendors Products
Mozilla
  • Firefox
  • Firefox Esr
  • Thunderbird
Redhat
  • Enterprise Linux
  • Rhel E4s
  • Rhel Eus

Configuration 1 [-]

OR cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
Package CPE Advisory Released Date
Red Hat Enterprise Linux 7
firefox-0:91.5.0-1.el7_9 cpe:/o:redhat:enterprise_linux:7 RHSA-2022:0124 2022-01-12T00:00:00Z
thunderbird-0:91.5.0-1.el7_9 cpe:/o:redhat:enterprise_linux:7 RHSA-2022:0127 2022-01-12T00:00:00Z
Red Hat Enterprise Linux 8
thunderbird-0:91.5.0-1.el8_5 cpe:/a:redhat:enterprise_linux:8 RHSA-2022:0129 2022-01-12T00:00:00Z
firefox-0:91.5.0-1.el8_5 cpe:/a:redhat:enterprise_linux:8 RHSA-2022:0130 2022-01-12T00:00:00Z
Red Hat Enterprise Linux 8.1 Update Services for SAP Solutions
firefox-0:91.5.0-1.el8_1 cpe:/a:redhat:rhel_e4s:8.1 RHSA-2022:0125 2022-01-12T00:00:00Z
thunderbird-0:91.5.0-1.el8_1 cpe:/a:redhat:rhel_e4s:8.1 RHSA-2022:0131 2022-01-12T00:00:00Z
Red Hat Enterprise Linux 8.2 Extended Update Support
thunderbird-0:91.5.0-1.el8_2 cpe:/a:redhat:rhel_eus:8.2 RHSA-2022:0123 2022-01-12T00:00:00Z
firefox-0:91.5.0-1.el8_2 cpe:/a:redhat:rhel_eus:8.2 RHSA-2022:0132 2022-01-12T00:00:00Z
Red Hat Enterprise Linux 8.4 Extended Update Support
firefox-0:91.5.0-1.el8_4 cpe:/a:redhat:rhel_eus:8.4 RHSA-2022:0126 2022-01-12T00:00:00Z
thunderbird-0:91.5.0-1.el8_4 cpe:/a:redhat:rhel_eus:8.4 RHSA-2022:0128 2022-01-12T00:00:00Z
References
Link Providers
https://bugzilla.mozilla.org/show_bug.cgi?id=1746720 cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2021-4140 cve-icon
https://www.cve.org/CVERecord?id=CVE-2021-4140 cve-icon
https://www.mozilla.org/en-US/security/advisories/mfsa2022-02/#CVE-2021-4140 cve-icon
https://www.mozilla.org/en-US/security/advisories/mfsa2022-03/#CVE-2021-4140 cve-icon
https://www.mozilla.org/security/advisories/mfsa2022-01/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2022-02/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2022-03/ cve-icon cve-icon
History

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'}
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