CVE-2026-54618: Jimprosser Obsidian-Web-Mcp

Critical severity, CVSS 9.4. EPSS: 0.5% chance of exploitation in the next 30 days.

Obsidian Web MCP is a secure remote MCP server for Obsidian vaults. Prior to 0.2.0, /oauth/authorize issues an authorization code without a login, consent, or session check, and /oauth/token can exchange that code for the static VAULT_MCP_TOKEN without authenticating a client. An unauthenticated remote caller who can reach the intended tunnel deployment can therefore call /mcp and use vault_read, vault_write, vault_search, vault_list, vault_move, and vault_delete against the entire vault. Optional PKCE does not prevent an attacker-initiated flow, and unauthenticated /oauth/register also exposes a client_credentials path by returning the configured VAULT_OAUTH_CLIENT_SECRET. This issue is fixed in version 0.2.0.

Affected products

• Jimprosser Obsidian-Web-Mcp: before 0.2.0 (fixed in 0.2.0)

Published 2026-09-17. Last modified 2026-09-30.