Older versions receive no security patches. Update to the latest release before reporting.

Do not open a public GitHub issue for security vulnerabilities.

Report security issues through one of these channels:

• Email: security@m365-mcp (PGP not yet published; include "SECURITY" in the subject line)
• GitHub private advisory: Open a private security advisory — this is the preferred channel

You will receive updates as the issue progresses. If you do not hear back within 72 hours, follow up via GitHub private advisory.

• Token cache file permissions: The token cache at ~/.config/m365-mcp/token-cache.json is written with 0o600 (owner read/write only) on every write and explicitly re-chmod'd to enforce this even if the file already existed. Any code path where this is not enforced — for example, if the cache directory is created with world-readable permissions or if an error path bypasses the chmod call — is in scope.
• Authentication flow issues: Vulnerabilities in the MSAL device code flow that could allow token theft or session hijacking.
• Microsoft Graph credential exposure: Any path where access tokens, refresh tokens, or client secrets could be written to logs, stdout, or error messages surfaced to the MCP client.
• MCP input validation bypasses: Inputs to tool handlers that bypass Zod schema validation and reach the Graph API or file system in an unsafe way (e.g., path traversal, injection into Graph filter strings).

• Microsoft Azure AD infrastructure, the Microsoft identity platform, or Graph API service availability — report those directly to Microsoft (https://msrc.microsoft.com).
• Issues that require physical access to the user's device or OS-level root/admin privileges.
• Social engineering or phishing attacks not specific to this codebase.
• Findings from automated scanners without a demonstrated impact.

Once a patch is released, reporters are credited in the CHANGELOG unless they request anonymity. There is no bug bounty program at this time.