CVE-2026-21521 Word Copilot Information Disclosure Vulnerability
An unauthorized attacker can disclose information over a network due to improper neutralization of escape sequences in Word Copilot.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-21521?
CVE-2026-21521 is a high-severity vulnerability in Microsoft 365 Word Copilot, published on 22 Jan 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Improper neutralization of escape, meta, or control sequences in Copilot allows an unauthorized attacker to disclose information over a network.
Weakness: CWE-150
Which versions are affected by CVE-2026-21521?
It affects 1 product.
Products include Microsoft 365 Word Copilot.
How do I fix CVE-2026-21521?
No fix has been published for CVE-2026-21521 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-21521 being exploited?
There is no known exploitation of CVE-2026-21521 in the wild and no public exploit code.
Other vulnerabilities in Microsoft 365 Word Copilot
Sources
Also known as GHSA-mmfw-g245-wgx2.