CVE-2026-65957
Helio: Dashboard sideband CORS origin allowlist matches hostnames by prefix, admitting attacker-controlled origins in open mode
Helio is an MCP proxy that sits between AI agents and the tools they use. Prior to version 0.8.0, the dashboard sideband (default 127.0.0.1:3100) validated CORS request origins by matching the hostname against a private-network string prefix (10., 172.16.–172.31., 192.168.) rather than validating an IP address. A public DNS name such as 192.168.attacker.com, 10.evil.io, or 172.16.pwn.example also satisfies that prefix, so the proxy echoed the attacker origin in Access-Control-Allow-Origin. This issue has been patched in version 0.8.0.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| helio gethelio |
< 0.8.0 (affected) | CNA: GitHub_M |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 6.9 medium |
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N | CNA: GitHub_M |
| 4.0 / 6.9 medium |
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD: [email protected] |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/gethelio/helio/security/advisories/GHSA-2c3r-q7gv-hp2mCNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/gethelio/helio/pull/121CNA: GitHub_M · x_refsource_MISC
- https://github.com/gethelio/helio/commit/4ca8329c38b0edbc5e4d782a4e3b0cfc5cd7782eCNA: GitHub_M · x_refsource_MISC
- https://github.com/gethelio/helio/releases/tag/v0.8.0CNA: GitHub_M · x_refsource_MISC
- https://github.com/gethelio/helio/commit/4ca8329c38b0edbc5e4d782a4e3b0cfc5cd7782e[email protected]
- https://github.com/gethelio/helio/pull/121[email protected]
- https://github.com/gethelio/helio/releases/tag/v0.8.0[email protected]
- https://github.com/gethelio/helio/security/advisories/GHSA-2c3r-q7gv-hp2m[email protected]
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