CVE-2026-63732

9router 0.4.59 (fixed in 0.4.60) contains a chain of vulnerabilities: a hardcoded default password (123456) that authenticates any fresh installation, a bypass of the LOCAL_ONLY network gate via a spoofed Host header, and unvalidated arguments passed to child_process.spawn() when registering MCP plugins. A remote, unauthenticated attacker can log in with the default credential, spoof the Host header to reach local-only routes, and register a malicious MCP plugin (e.g. node -e <payload>) to achieve arbitrary code execution on the host operating system when the plugin's SSE endpoint is triggered.

CVSS 4.0

9.4CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CVSS 3.1

9.9CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS

1.0% chance of exploitation in the next 30 days; higher than 62% of CVEs (scores of 2026-10-25)

CWE

CWE-78

Published

2026-07-23

Modified

2026-10-24

Record from

the NVD, synced 2026-10-24

References

• https://github.com/decolua/9router/security/advisories/GHSA-4922-8r65-fq26
• https://www.vulncheck.com/advisories/9router-before-remote-code-execution-via-default-password

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