What is CVE-2026-21521?

CVE-2026-21521 is a security advisory published by Microsoft Security Response Center (MSRC) with Critical severity. Word Copilot Information Disclosure Vulnerability

Which CVE IDs does CVE-2026-21521 cover?

CVE-2026-21521 covers the following CVE IDs: CVE-2026-21521. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of CVE-2026-21521?

CVE-2026-21521 has a CVSS v3 base score of 7.4, published by Microsoft Security Response Center (MSRC).

Which products are affected by CVE-2026-21521?

CVE-2026-21521 affects 1 product, including: Microsoft 365 Word Copilot.

CVE-2026-21521CriticalCVSS 7.4

Word Copilot Information Disclosure Vulnerability

Vendor

Microsoft Security Response Center (MSRC)

Published

June 2, 2026

Last Modified

—

🔗 CVE IDs covered (1)

CVE-2026-21521 →

📋 Description

Improper neutralization of escape, meta, or control sequences in Copilot allows an unauthorized attacker to disclose information over a network.

🎯 Affected products1

Microsoft 365 Word Copilot

🔗 References (1)

advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21521