CVE-2026-21521 json
Word Copilot Information Disclosure Vulnerability
published 9mo ago modified 3mo ago also EUVD-2026-4498
- cvss
- 7.4
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.6%
- EPSS 0.6% chance of exploitation in 30 days, percentile 49%
- public exploits
- 0
- none known
Summary
Improper neutralization of escape, meta, or control sequences in Copilot allows an unauthorized attacker to disclose information over a network.
Patch / fix
Is CVE-2026-21521 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 9mo ago
Exploit prediction
0.61% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.4 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C |
| CNA | 3.1 | 7.4 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N |
Affected products
- Microsoft Microsoft 365 Word Copilot
Classification
- Weakness
-
- CWE-150 Improper Neutralization of Escape, Meta, or Control Sequences
References
-
msrc.microsoft.com
/update-guide/vulnerability/CVE-2026-21521
vendor-advisory, patch
Sources
- CVE List CVE-2026-21521
- NVD CVE-2026-21521
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