# CVE-2026-77366: obsidian-tc cross-vault authorization bypass

Source: https://junglewise.ai/threats/cve-2026-77366-obsidian-tc-is-a-governed-agent-ready-model-context-protocol  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-12. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-77366 · Severity: critical · CVSS 9.9 · Published 2026-10-12

obsidian-tc is a Model Context Protocol server that allows AI agents to interact with Obsidian note vaults. Prior to version 1.3.1, any valid authentication token could access all configured vaults by specifying a different vault's identifier in tool arguments, allowing unauthorized reading, writing, or deletion of vault contents. The fix ensures tokens are bound to specific vaults and validates vault identity before processing requests.

Technologies: [obsidian-tc (npm)](https://junglewise.ai/threats/technologies/npm-obsidian-tc), [The-40-Thieves Obsidian-Tc](https://junglewise.ai/threats/technologies/obsidian-tc). Vendors: [npm](https://junglewise.ai/threats/vendors/npm), [The-40-Thieves](https://junglewise.ai/threats/vendors/the-40-thieves).

## Quick answers

**Is CVE-2026-77366 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-77366 being exploited in the wild.

**How severe is CVE-2026-77366?** Critical severity, with a CVSS score of 9.9, published 12 October 2026.

**Which products and versions are affected?** obsidian-tc (npm) < 1.3.1, SEMVER:introduced=0,fixed=1.3.1; The-40-Thieves Obsidian-Tc before 1.3.1.

**Is there a fix for CVE-2026-77366?** Yes. obsidian-tc (npm): upgrade to 1.3.1 or later. Until then: In multi-vault HTTP deployments, mint separate authentication tokens for each vault by including a vault claim; tokens without a vault claim are confined to the server's default vault only.</anigation>
<parameter name="timeline">[{"kind":"disclosed","at":"2026-10-12"},{"kind":"patched","at":"2026-07-01","note":"Fix committed to main branch"}] Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-77366 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-77366?** Check whether you run obsidian-tc (npm) or The-40-Thieves Obsidian-Tc at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- obsidian-tc (npm): upgrade to 1.3.1 or later

  ```sh
  npm install obsidian-tc@1.3.1
  ```


In multi-vault HTTP deployments, mint separate authentication tokens for each vault by including a vault claim; tokens without a vault claim are confined to the server's default vault only.</anigation>
<parameter name="timeline">[{"kind":"disclosed","at":"2026-10-12"},{"kind":"patched","at":"2026-07-01","note":"Fix committed to main branch"}]

## Technical details

The vulnerability is an authorization bypass in tool dispatch where caller-supplied vault identifiers are not validated against the token's bound vault. The JWT contained no vault claim, and the folder access-control list was globally shared, allowing any valid HTTP bearer token to invoke ~90 vault tools against any configured vault. Only the resources/read tool performed proper validation. Version 1.3.1 adds a vault claim to the JWT, binds HTTP callers to their token's vault via context, and implements a guard in runDispatch that rejects mismatched vault arguments.

## Affected products

- The-40-Thieves obsidian-tc before 1.3.1

## Identifiers

- CVE-2026-77366
- GHSA-84c9-qqpq-2pq5

## References

- [https://github.com/The-40-Thieves/obsidian-tc/commit/38b4992e87dc2715564236e1a42d005ab05a0194](https://github.com/The-40-Thieves/obsidian-tc/commit/38b4992e87dc2715564236e1a42d005ab05a0194)
- [https://github.com/The-40-Thieves/obsidian-tc/pull/72](https://github.com/The-40-Thieves/obsidian-tc/pull/72)

## Related threats

- [obsidian-tc entity operations data loss through unserialized SQLite writes](https://junglewise.ai/threats/cve-2026-115478-obsidian-tc-is-a-governed-agent-ready-model-context-protocol)
- [obsidian-tc improper authorization in dispatch-gated tool execution](https://junglewise.ai/threats/cve-2026-115477-obsidian-tc-is-a-governed-agent-ready-model-context-protocol)
- [obsidian-tc information disclosure via bridge tools ACL bypass](https://junglewise.ai/threats/cve-2026-77362-obsidian-tc-is-a-governed-agent-ready-model-context-protocol)
- [obsidian-tc ACL bypass via symlink path resolution](https://junglewise.ai/threats/cve-2026-77361-obsidian-tc-is-a-governed-agent-ready-model-context-protocol)
- [obsidian-tc path traversal via undefined ACL defaults](https://junglewise.ai/threats/cve-2026-77364-obsidian-tc-is-a-governed-agent-ready-model-context-protocol)