What is CVE-2026-54618?

CVE-2026-54618 is a critical-severity vulnerability in Jimprosser Obsidian-Web-Mcp, classified under Missing Authentication for Critical Function. CVSS score: 9.4/10. Published 2026-09-17.

How severe is CVE-2026-54618?

Critical severity. CVSS v3 base score is 9.4 out of 10.

Auth bypass in Jimprosser Obsidian-Web-Mcp

CVE-2026-54618

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.

Vulnerability class: Broken Authentication

CVSS v3 metric

CVSS v3 base score 9.4 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L.

Affected products

Jimprosser Obsidian-web-mcp — versions < 0.2.0

Weakness classification (CWE)

References

security-advisories@github.com (x_refsource_CONFIRM)
security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-54618?: CVE-2026-54618 is a critical-severity vulnerability in Jimprosser Obsidian-Web-Mcp, classified under Missing Authentication for Critical Function. CVSS score: 9.4/10. Published 2026-09-17.
How severe is CVE-2026-54618?: Critical severity. CVSS v3 base score is 9.4 out of 10.