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Command Injection Information Disclosure in M365 Copilot
CVE-2026-24299 is an information disclosure vulnerability in M365 Copilot caused by improper neutralization of special elements used in a command. The flaw is classified as command injection and allows attacker-controlled input to influence command-like processing within the service, resulting in disclosure of sensitive information over the network. Available reporting associates this issue with prompt-injection-driven abuse paths in Microsoft 365 Copilot, including exfiltration of data accessible to the victim’s Copilot context. Microsoft has described the issue as a cloud service vulnerability and stated that it has been fully mitigated server-side.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation allows unauthorized disclosure of sensitive information available through the affected M365 Copilot context. Reported impact is limited to confidentiality: high confidentiality impact with no stated integrity or availability impact. In practical terms, exploitation could expose data the victim is authorized to access through Copilot-integrated workflows, enabling remote exfiltration over the network.
If you can’t patch tonight, do this now.
No direct customer-side patching action is required because the vulnerability has been fully mitigated by Microsoft in the service. As defense-in-depth for similar Copilot injection and data-exfiltration scenarios, organizations can reduce exposed data by limiting unnecessary Copilot-connected data sources, reviewing access permissions to sensitive content, constraining assistant access to only required services, and monitoring for anomalous Copilot-mediated access patterns and suspicious link-driven workflows that may attempt to trigger malicious prompt or command execution paths.
Patch, then assume compromise.
Microsoft has already remediated this vulnerability in the M365 Copilot service. The fix was applied server-side as a cloud service mitigation, and Microsoft stated that no customer action is required. Where organizational process allows, defenders should verify that users are operating against the current service and monitor Microsoft security communications for any follow-on hardening guidance related to Copilot injection abuse.
No public exploits tracked yet. Mallory keeps watching.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
21 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.