Mozilla Firefox up to 95 XSLT sandbox

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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8.0$0-$5k0.00

Summaryinfo

A vulnerability was found in Mozilla Firefox up to 95. It has been rated as critical. Affected by this vulnerability is an unknown functionality of the component XSLT Handler. The manipulation leads to sandbox. This vulnerability is referenced as CVE-2021-4140. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 95 (Web Browser). It has been rated as critical. This issue affects an unknown function of the component XSLT Handler. The manipulation with an unknown input leads to a sandbox vulnerability. Using CWE to declare the problem leads to CWE-265. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The weakness was published 01/11/2022 by Peter Van der Beken as Bug 1746720 as confirmed advisory (Website). The advisory is shared at bugzilla.mozilla.org. The advisory contains:

It was possible to construct specific XSLT markup that would be able to bypass an iframe sandbox.
The identification of this vulnerability is CVE-2021-4140. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 04/16/2025). MITRE ATT&CK project uses the attack technique T1611 for this issue.

Upgrading to version 96 eliminates this vulnerability. A possible mitigation has been published immediately after the disclosure of the vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.1
VulDB Meta Temp Score: 8.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 10.0
NVD Vector: 🔍

CVSSv2info

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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Sandbox
CWE: CWE-265 / CWE-264
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Upgrade: Firefox 96

Timelineinfo

12/20/2021 🔍
01/11/2022 +22 days 🔍
01/11/2022 +0 days 🔍
09/29/2022 +261 days 🔍
04/16/2025 +930 days 🔍

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: Bug 1746720
Researcher: Peter Van der Beken
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2021-4140 (🔍)
GCVE (CVE): GCVE-0-2021-4140
GCVE (VulDB): GCVE-100-209825

Entryinfo

Created: 09/29/2022 15:22
Updated: 04/16/2025 18:35
Changes: 09/29/2022 15:22 (17), 09/29/2022 15:26 (29), 10/25/2022 15:06 (1), 04/16/2025 18:35 (27)
Complete: 🔍
Cache ID: 216::103

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