Vulnerability Monitor

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CVE-2021-38503

The iframe sandbox rules were not correctly applied to XSLT stylesheets, allowing an iframe to bypass restrictions such as executing scripts or navigating the top-level frame. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

Security Impact Summary

This vulnerability carries a CRITICAL severity rating with a CVSS v3.1 score of 10.0, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 4 products from mozilla, from mozilla, from mozilla and 1 other, organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.

Published

2021-12-08T22:15:08.737

Last Modified

2024-11-21T06:17:15.767

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 10.0 (CRITICAL)

CVSSv2 Vector

AV:N/AC:L/Au:N/C:P/I:P/A:P

Access Vector: NETWORK
Access Complexity: LOW
Authentication: NONE
Confidentiality Impact: PARTIAL
Integrity Impact: PARTIAL
Availability Impact: PARTIAL

Exploitability Score

10.0

Impact Score

6.4

Weaknesses

Type: Primary
CWE-863

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Application	mozilla	firefox	< 94.0	Yes
Application	mozilla	firefox_esr	< 91.3	Yes
Application	mozilla	thunderbird	< 91.3	Yes
Operating System	debian	debian_linux	9.0	Yes
Operating System	debian	debian_linux	10.0	Yes
Operating System	debian	debian_linux	11.0	Yes

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1729517 Issue Tracking, Permissions Required, Vendor Advisory ([email protected])
https://lists.debian.org/debian-lts-announce/2021/12/msg00030.html Mailing List, Third Party Advisory ([email protected])
https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html Mailing List, Third Party Advisory ([email protected])
https://security.gentoo.org/glsa/202202-03 Third Party Advisory ([email protected])
https://security.gentoo.org/glsa/202208-14 Third Party Advisory ([email protected])
https://www.debian.org/security/2021/dsa-5026 Third Party Advisory ([email protected])
https://www.debian.org/security/2022/dsa-5034 Third Party Advisory ([email protected])
https://www.mozilla.org/security/advisories/mfsa2021-48/ Vendor Advisory ([email protected])
https://www.mozilla.org/security/advisories/mfsa2021-49/ Vendor Advisory ([email protected])
https://www.mozilla.org/security/advisories/mfsa2021-50/ Vendor Advisory ([email protected])
https://bugzilla.mozilla.org/show_bug.cgi?id=1729517 Issue Tracking, Permissions Required, Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://lists.debian.org/debian-lts-announce/2021/12/msg00030.html Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html Mailing List, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://security.gentoo.org/glsa/202202-03 Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://security.gentoo.org/glsa/202208-14 Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.debian.org/security/2021/dsa-5026 Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.debian.org/security/2022/dsa-5034 Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.mozilla.org/security/advisories/mfsa2021-48/ Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.mozilla.org/security/advisories/mfsa2021-49/ Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.mozilla.org/security/advisories/mfsa2021-50/ Vendor Advisory (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For mozilla's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.