CVSS 4.0
6.9 mediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:NCVE-2026-65957 Helio: Dashboard sideband CORS origin allowlist matches hostnames by prefix, admitting attacker-controlled origins in open mode
Medium (6.9) in gethelio helio. EPSS 0.2% estimated probability of exploitation activity in the next 30 days.
On this page
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.
Severity
- EPSS
- 0.2% estimated probability of exploitation activity in the next 30 days; 13th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: yes · Technical impact: partial, assessed 2026-11-12. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- CWEs
- CWE-346 Origin Validation Error
CWE-942 Permissive Cross-domain Security Policy with Untrusted Domains - Published
- Modified
- Assigned by
- GitHub_M (CNA)
- NVD analysis
- Deferred: the NVD does not plan to analyze it
- Record from
- the NVD, synced
Ask an AI about this CVE
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Explain CVE-2026-65957 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-65957?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-65957?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-65957 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.
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Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| gethelio helio | < 0.8.0 |
Attack patterns (CAPEC)
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits. More on the page of CWE-346 (16).
History
- The NVD deferred its analysis
Changes since this site first stored the record. The same for every record: /api/public/changes.