# CVE-2026-54618

## Summary

- **CVE ID:** CVE-2026-54618
- **Severity:** CRITICAL
- **CVSS Score:** 9.4 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L)
- **CWE:** CWE-306, CWE-522, CWE-601
- **Published:** Sep 17, 2026
- **Last Modified:** Sep 17, 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.

## Affected Products

- jimprosser — obsidian-web-mcp (< 0.2.0)

## References

- [CNA](https://github.com/jimprosser/obsidian-web-mcp/security/advisories/GHSA-hwhg-mrjc-8g43)
- [CNA](https://github.com/jimprosser/obsidian-web-mcp/pull/30)
- [CNA](https://github.com/jimprosser/obsidian-web-mcp/commit/e4924f096ee7494a7999d6c0cceca9be08e48eef)
- [CNA](https://github.com/jimprosser/obsidian-web-mcp/releases/tag/v0.2.0)

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._