How severe is CVE-2026-77363?

CVE-2026-77363 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-77363?

CVE-2026-77363 affects the following packages: obsidian-tc (npm). Ecosystems affected: npm.

How do I fix CVE-2026-77363?

Update obsidian-tc to 1.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-77363 is resolved across your whole dependency graph.

How do I detect CVE-2026-77363 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for obsidian-tc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-77363 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-77363 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-77363 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-77363?

CVE-2026-77363 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 5th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-77363?

CVE-2026-77363 is classified as CWE-346 (CWE-346), CWE-1385 (CWE-1385). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-77363 published, and has it been updated?

CVE-2026-77363 was published on October 12, 2026 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

HIGH severity

CVE-2026-77363 — obsidian-tc

HIGHFix: The-40-Thieves/obsidian-tc@6428bfe

CVE-2026-77363 is a high-severity (CVSS 8.8) CWE-346 vulnerability in obsidian-tc. A fix is available for obsidian-tc — see the affected versions and patch details below.

obsidian-tc Streamable HTTP transport permits cross-origin loopback vault access

Also known asGHSA-pqh8-4pj7-32xx

Published

Oct 12, 2026

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-77363.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs5th percentile — riskier than 5% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-77363 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

📦obsidian-tc

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Impact

The Streamable HTTP transport was constructed without enableDnsRebindingProtection/allowedHosts/allowedOrigins and performed no Origin-header validation. With the documented auth.mode: "none" loopback default, a drive-by web page could POST http://127.0.0.1/mcp and receive caller http-local with scopes ["*"] — full vault read/write — via DNS rebinding / a forged Origin.

Patches

Fixed in 1.3.1. Upgrade to >= 1.3.1. The transport now enables DNS-rebinding protection and allowed hosts/origins and returns HTTP 403 on an invalid Origin (per MCP 2025-11-25).

Workarounds

Do not expose the HTTP transport with auth.mode: "none"; require JWT auth, or bind to a non-loopback interface behind a proxy that validates Origin.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`obsidian-tc`	all versions	1.3.1`npm install obsidian-tc@1.3.1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for obsidian-tc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update obsidian-tc to 1.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-77363 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact The Streamable HTTP transport was constructed without `enableDnsRebindingProtection`/`allowedHosts`/`allowedOrigins` and performed no `Origin`-header validation. With the documented `auth.mode: "none"` loopback default, a **drive-by web page could `POST http://127.0.0.1/mcp`** and receive caller `http-local` with scopes `["*"]` — full vault read/write — via DNS rebinding / a forged Origin. ### Patches Fixed in **1.3.1**. Upgrade to `>= 1.3.1`. The transport now enables DNS-rebinding protection and allowed hosts/origins and returns HTTP 403 on an invalid Origin (per MCP 2025-11-25).