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Case File

CVE-2021-38503

CRITICAL · CVSS 10 EPSS 3.83%

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-12-08 · 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-2021-38503
Severity
CRITICAL
CVSS
10
EPSS
3.83%
Firefox

Original NVD Description

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.

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