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CVE-2026-81094

9.1 · CRITICAL

The mcp-router CLI served its MCP aggregator on every interface and enforced authentication only when the operator asked for it.

Published Aug 27, 2026CWE-306EPSS 0.61%

Overview

CVE-2026-81094 is a critical-severity vulnerability. It was published on August 27, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

The mcp-router CLI served its MCP aggregator on every interface and enforced authentication only when the operator asked for it. The serve command in apps/cli/src/commands/serve.ts defaulted its host to the all-interfaces address on a fixed port, and required a token only when the corresponding flag was supplied, so a default invocation exposed the aggregator, and every MCP server it fronted, to anyone able to reach the port. Release 0.6.3 defaults the host to the loopback address and refuses to start without a token whenever the host it is given is not a loopback address; no earlier release carries either check.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/mcp-router/mcp-routerGitHubgithub.com/mcp-router/mcp-router/blob/v0.6.3/apps/cli/src/commands/serve.ts#L105GitHubgithub.com/mcp-router/mcp-router/commit/4c4642cfd274097ec8b33ecd3047390829c79d35GitHubgithub.com/mcp-router/mcp-router/security/advisories/GHSA-rx55-5c7h-r56rRefwww.vulncheck.com/advisories/mcp-router-cli-before-0.6.3-binds-the-mcp-aggregator-to-all-interfaces-without-requiring-authentication

How CyberStrike helps

Frequently asked questions

What is CVE-2026-81094?

CVE-2026-81094 is a critical-severity vulnerability. It was published on August 27, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-81094?

This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-81094?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-81094?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-81094 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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