CVE-2026-26129 M365 Copilot Information Disclosure Vulnerability
An unauthorized attacker can disclose information via command injection in Microsoft 365 Copilot Business Chat.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-26129?
CVE-2026-26129 is a high-severity vulnerability in Microsoft 365 Copilot's Business Chat, published on 7 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.
Weakness: CWE-138
Which versions are affected by CVE-2026-26129?
It affects 1 product.
Products include Microsoft 365 Copilot Chat.
How do I fix CVE-2026-26129?
No fix has been published for CVE-2026-26129 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-26129 being exploited?
There is no known exploitation of CVE-2026-26129 in the wild and no public exploit code.
Other vulnerabilities in Microsoft 365 Copilot's Business Chat
- CVE-2026-26137 Microsoft Exchange Elevation of Privilege Vulnerability
- CVE-2025-59272 Copilot Information Disclosure Vulnerability
- CVE-2025-59286 Copilot Information Disclosure Vulnerability
- CVE-2026-78501 Microsoft 365 Copilot Business Chat Information Disclosure Vulnerability
- CVE-2025-53787 Microsoft 365 Copilot BizChat Information Disclosure Vulnerability
Sources
Also known as GHSA-hpvr-rjcg-4q53.