CVE-2026-54618
Obsidian Web MCP: Unauthenticated vault access: /oauth/authorize auto-approves without authenticating the user
- State
- Published
- Severity
- 9.4 Critical
- Published
- Sep 17, 2026
- Updated
- Sep 24, 2026
- Reserved
- Jun 15, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.4 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
obsidian-web-mcpjimprosser |
|
References
- https://github.com/jimprosser/obsidian-web-mcp/security/advisories/GHSA-hwhg-mrjc-8g43
- https://github.com/jimprosser/obsidian-web-mcp/pull/30
- https://github.com/jimprosser/obsidian-web-mcp/commit/e4924f096ee7494a7999d6c0cceca9be08e48eef
- https://github.com/jimprosser/obsidian-web-mcp/releases/tag/v0.2.0
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