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CVE-2026-115477EUVD-2026-109082GHSA-737X-CWFR-5VVC

obsidian-tc: Declined human-in-the-loop confirmations can permit destructive calls over HTTP

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 1.31.4
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: poc
  • Automatable: no
  • Technical impact: partial

Summary

obsidian-tc, a Model Context Protocol server for Obsidian vaults, is affected when run over Streamable HTTP with JWT authentication configured. The flaw let a client complete destructive vault operations, such as deleting or overwriting notes, after a human had declined or cancelled the required confirmation, so those changes could happen without the user's approval.

Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.

Read the original description

obsidian-tc is a governed, agent-ready Model Context Protocol server for Obsidian vaults. From 1.13.0 until 1.31.4, on a Streamable HTTP deployment with `auth.jwtSecret` configured and a 2026-07-28-era client declaring `elicitation.form` support, a dispatch-gated tool call offered an `inputRequired` confirmation could still complete after the human declined or cancelled, or the elicitation response was omitted or malformed, provided the client echoed the validly bound `requestState` on resubmission. The server trusted an authentic, call-bound state as proof of approval even though that state was minted before the `elicitation/create` leg was asked and proved only that the resubmission belonged to the same call. A client behaving incorrectly or under an attacker's control could therefore execute dispatch-gated destructive vault operations without the human's approval, while still requiring the caller's ordinary tool permissions. Only tools marked `destructive: true` or requiring a scope with a human-in-the-loop floor were reachable through this bypass. The sixteen handler-side conditionally gated tools, including `write_note` overwrite and `move_note`, did not read elicitation state on the modern wire and let neither approval nor decline through that path. Affected deployments using stdio or leaving `auth.jwtSecret` unset instead used the CLI `elicit_token` fallback and did not offer this `requestState` round trip. The fix does not prevent a malicious client from reporting a fabricated approval, because the server cannot verify that the client displayed the form or that a human saw it. This issue is fixed in version 1.31.4.

Timeline

  1. CVE published
  2. First seen by cve.now
  3. CISA SSVC assessment

    Exploitation: poc · Automatable: no · Technical impact: partial

  4. Record last updated

Affected versions

  • The-40-Thieves obsidian-tc

    From 1.13.0 · fixed in 1.31.4

  • obsidian-tcnpm

    From 1.13.0 · fixed in 1.31.4

References 6

GitHub · The-40-Thieves/obsidian-tc