CVE-2026-77366: obsidian-tc tokens can access arbitrary configured vaults

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.3%, percentile 22: FIRST’s model estimates a 0.3% chance of exploitation activity in the next 30 days, higher than 22% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes obsidian-tc (npm) < 1.3.1, fixed in 1.3.1. Check your lockfile, including transitive dependencies.

What it is

obsidian-tc is a governed, agent-ready Model Context Protocol server for Obsidian vaults. Prior to 1.3.1, tool dispatch does not compare the caller-controlled input.vault value with the vault bound to the caller, the JSON Web Token (JWT) has no vault claim, and the folder access-control list is shared globally. Any valid token can therefore select another configured vault and read, write, or delete its contents through affected tools. Version 1.3.1 fixes the vulnerability by binding tokens and request context to a vault and rejecting mismatched input.vault values before scope checks.

From the GitHub advisory

Impact Tool dispatch did not check the caller-supplied input.vault against the caller's bound vault (ctx.vaultId); the folder ACL was a single global instance and the JWT carried no vault claim. As a result, any valid token could read, write, or delete any configured vault by passing input.vault, defeating multi-tenant isolation across ~90 tool sites. (resources/read was the only surface that already guarded this.)

Patches Fixed in 1.3.1 (the fix was developed on the v1.3.0 tag, which never published to npm; 1.3.1 is the first published release with the fix). Upgrade to >= 1.3.1.

Workarounds Run a single vault per server process, or isolate each tenant on a separate process/credential.

Fix A central input.vault === ctx.vaultId guard was added in dispatch before the scope check.

Weakness type: CWE-639, CWE-863.

Product: obsidian-tc (npm) · Assigned by: GitHub_M · Published: 2026-10-12

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-23): 0.31% probability of exploitation activity in the next 30 days; percentile 22.

Timeline

• 2026-10-12 — CVE record published by GitHub_M
• 2026-10-13 — CVE record last updated
• 2026-10-23 — GitHub-reviewed advisory GHSA-84c9-qqpq-2pq5 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-84c9-qqpq-2pq5 github.com
2. CVE.org record CVE-2026-77366 cve.org
3. NVD entry CVE-2026-77366 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. nvd.nist.gov nvd.nist.gov

Critical npm advisories · Today’s Security Digest