CVE-2026-54618
CriticalCVSS 9.4Summary
Obsidian Web MCP prior to 0.2.0 allows an unauthenticated remote attacker to obtain an authorization code without login and exchange it for the static VAULT_MCP_TOKEN. This grants full access to vault operations including read, write, search, move, and delete.
Risk Assessment
An attacker can read, modify, or delete the entire Obsidian vault content, causing a serious breach of data confidentiality and integrity.
Recommendation
Update Obsidian Web MCP to version 0.2.0 or later, which fixes this vulnerability.
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Original NVD description (English source)
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.