CVE-2026-21223
Published: 16 January 2026
Summary
CVE-2026-21223 is a high-severity Improper Privilege Management (CWE-269) vulnerability in Microsoft Edge Chromium. Its CVSS base score is 7.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 8.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and AC-6 (Least Privilege).
Deeper analysis
CVE-2026-21223 is an improper privilege management vulnerability affecting Microsoft Edge (Chromium-based), published on 2026-01-16T22:16:25.983. It enables an authorized attacker to bypass a security feature locally and is classified under CWE-269: Improper Privilege Management. The vulnerability has a CVSS v3.1 base score of 7.1, reflecting attack vector (AV:L), low attack complexity (AC:L), low privileges required (PR:L), no user interaction (UI:N), unchanged scope (S:U), high confidentiality impact (C:H), high integrity impact (I:H), and no availability impact (A:N).
The attack requires local access and low-level privileges, allowing exploitation with low complexity and no user interaction. A successful attacker can achieve high confidentiality and integrity impacts by bypassing the security feature, potentially leading to unauthorized data access or modification within the affected Edge environment.
Mitigation details are available in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21223.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-3111
Vulnerability details
Improper privilege management in Microsoft Edge (Chromium-based) allows an authorized attacker to bypass a security feature locally.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Improper privilege management in Edge enables local bypass of a security feature with low privileges, directly facilitating exploitation for privilege escalation and UAC bypass mechanisms.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly counters the improper privilege management flaw by restricting Edge processes and users to the minimum privileges needed, blocking local bypass of the security feature.
Enforces access control policies on all Edge operations so an authorized local attacker cannot bypass the intended security feature to gain elevated confidentiality or integrity.
Requires a tamper-proof reference monitor to mediate every access request inside Edge, preventing the unauthorized privilege escalation described in the CVE.