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CVE-2026-65957— Helio: Dashboard sideband CORS origin allowlist matches hostnames by prefix, admitting attacker-controlled origins in open mode

Quick assessment

Affected
gethelio helio
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Helio 是一个位于 AI 代理与其所用工具之间的 MCP 代理。在 0.8.0 版本之前，其仪表板旁路通道（默认监听 127.0.0.1:3100）在验证跨域资源共享（CORS）请求来源时，仅通过匹配主机名是否以私有网络字符串前缀（如 10.、172.16.–172.31.、192.168.）开头来进行判断，而未对 IP 地址本身进行验证。因此，诸如 192.168.attacker.com、10.evil.io 或 172.16.pwn.example 等公共域名也能满足该前缀匹配条件，导致代理在响应中将攻击

CVSS 6.9 · Medium

Possible ATT&CK Techniques 1 AI

T1566.002 · Spearphishing Link
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I. Basic Information for CVE-2026-65957

Vulnerability Information
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Vulnerability Title
Helio: Dashboard sideband CORS origin allowlist matches hostnames by prefix, admitting attacker-controlled origins in open mode
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
源验证错误
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
gethelio helio < 0.8.0 -

II. Public POCs for CVE-2026-65957

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III. Intelligence Information for CVE-2026-65957

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Other References for CVE-2026-65957 (4)

IV. Related Vulnerabilities

Same weakness: CWE-346