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Case File

CVE-2021-4140

CRITICAL · CVSS 10 EPSS 1.34%

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2022-12-22 · Last synced 2026-08-04

CyberRota Analysis

This is a critical severity vulnerability with a CVSS score of 10.0. It affects Firefox.

CVE
CVE-2021-4140
Severity
CRITICAL
CVSS
10
EPSS
1.34%
Firefox

Original NVD Description

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.

Related CVEs

Other vulnerabilities affecting the same vendor(s)

CVE-2026-16412 CRITICAL CVE-2026-16411 CRITICAL CVE-2026-16410 CRITICAL CVE-2026-16409 HIGH CVE-2026-16408 CRITICAL CVE-2026-16407 CRITICAL