Paper/Archive/CVE-2026-54618

CVE-2026-54618

jimprosser obsidian-web-mcp — Obsidian Web MCP: Unauthenticated vault access: /oauth/authorize auto-approves without authenticating the user

EPSS 0.5%public exploit CVSS 9.4

critical.is priorityof 100

CVSS 9.4 (CNA)9.4 / 10 × 3028.2 Not in CISA KEV+300.0 EPSS percentile 43.3.433 × 208.7 Exploit: SSVC poc+1010.0 SSVC exploitation: poc+100.0

Description · from the CVE record

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

ProductAffectedFixed inSource

obsidian-web-mcp< 0.2.0–CNA

Scores by source

GitHub_M (CNA)9.4CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

CISA ADPSSVCExploitation: poc · Automatable: yes · Technical impact: total

References

exploitgithub.com/jimprosser/obsidian-web-mcp/security/advisories/GHSA-hwhg-mrjc-8g43 refgithub.com/jimprosser/obsidian-web-mcp/pull/30 refgithub.com/jimprosser/obsidian-web-mcp/commit/e4924f096ee7494a7999d6c0cceca9be08e48eef refgithub.com/jimprosser/obsidian-web-mcp/releases/tag/v0.2.0