{"affected":[{"product":"helio","source":"CNA: GitHub_M","vendor":"gethelio","versions":[{"status":"affected","version":"< 0.8.0"}]}],"cveId":"CVE-2026-65957","cwes":["CWE-346","CWE-942"],"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.","epss":{"date":"2026-11-12","percentile":0.12955,"score":0.00222},"exploits":[],"kev":null,"metrics":[{"score":6.9,"severity":"medium","source":"CNA: GitHub_M","vector":"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","version":"4.0"},{"score":6.9,"severity":"medium","source":"NVD: security-advisories@github.com","vector":"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","version":"4.0"}],"modifiedAt":1794506140123,"publishedAt":1794429381626,"references":[{"source":"CNA: GitHub_M","tags":["x_refsource_CONFIRM"],"url":"https://github.com/gethelio/helio/security/advisories/GHSA-2c3r-q7gv-hp2m"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/gethelio/helio/pull/121"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/gethelio/helio/commit/4ca8329c38b0edbc5e4d782a4e3b0cfc5cd7782e"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/gethelio/helio/releases/tag/v0.8.0"},{"source":"security-advisories@github.com","tags":[],"url":"https://github.com/gethelio/helio/commit/4ca8329c38b0edbc5e4d782a4e3b0cfc5cd7782e"},{"source":"security-advisories@github.com","tags":[],"url":"https://github.com/gethelio/helio/pull/121"},{"source":"security-advisories@github.com","tags":[],"url":"https://github.com/gethelio/helio/releases/tag/v0.8.0"},{"source":"security-advisories@github.com","tags":[],"url":"https://github.com/gethelio/helio/security/advisories/GHSA-2c3r-q7gv-hp2m"}],"remediation":[],"revision":"9418a46cce1c6ce84d108180bd545b4e7a219066efb59c77807acae1bf92debd","sources":[{"modifiedAt":1794506140123,"name":"CNA: GitHub_M","retrievedAt":1794507105380,"url":"https://www.cve.org/CVERecord?id=CVE-2026-65957"},{"modifiedAt":1794431806243,"name":"NVD","retrievedAt":1794443547965,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-65957"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1794507135929,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-65957"}],"ssvc":{"assessedAt":1794501490952,"automatable":"yes","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"Helio: Dashboard sideband CORS origin allowlist matches hostnames by prefix, admitting attacker-controlled origins in open mode","updatedAt":1794507135929}