CVE-2026-21521

Name: CVE-2026-21521
Creator: NVD / NIST
Published: 2026-01-22T23:15:57.823+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.4/10EPSS 0.50%

Last modified Jun 17, 2026

CVE-2026-21521 is a high-severity vulnerability rated 7.4/10 on the CVSS scale. Improper neutralization of escape, meta, or control sequences in Copilot allows an unauthorized attacker to disclose information over a network.. EPSS estimates a 0.50% chance of exploitation in the next 30 days.

Description

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

Metrics

CVSS 3.1

7.4/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

EPSS Probability

0.50%

39.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-150

Affected Software

Vendor	Product	Versions
Microsoft	365 Word Copilot	All versions

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21521Vendor Advisory

Timeline

Published: Jan 22, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-21521?

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

How severe is CVE-2026-21521?

CVE-2026-21521 has a CVSS score of 7.4/10 (HIGH severity). The EPSS model estimates a 0.50% probability of exploitation in the next 30 days.

How do I fix CVE-2026-21521?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-21521?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST