Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests
Key facts
- Attack vector
- —
- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
- Security bypass, Tampering
- Confidentiality · integrity · availability
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- Fix status
- Fixed
No CVSS vector from any source. Fix status from GitHub. Impact type from CWE-346 and CWE-352.
Summary
## Impact Uni-CLI versions before 0.225.2 exposed the legacy JSON-RPC-over-HTTP MCP transport on loopback without validating browser Origin headers before routing requests. A malicious web page could send a CORS simple POST request, such as text/plain, to the local /mcp endpoint and deliver a JSON-RPC body to the dispatcher. If the user had started the local MCP HTTP transport, that page could drive tools/call requests against the user's local Uni-CLI server. The Streamable HTTP transport already enforced this browser-to-localhost boundary. The legacy stateless HTTP path did not, so the two HTTP transports had drifted. This issue is about the browser-to-localhost boundary; it does not change Uni-CLI's local-code-execution trust model. ## Patches Version 0.225.2 fixes the issue by moving the Origin policy into a shared guard and applying it before routing in both HTTP transports. Non-loopback browser Origins are rejected with HTTP 403 before health, OAuth, or /mcp dispatch runs. Non-browser clients that omit Origin remain supported. ## Workarounds Upgrade to 0.225.2 or later. If upgrading is not immediately possible, do not expose the legacy HTTP MCP transport to browser-originated traffic; use the default stdio transport or the Streamable HTTP transport instead. ## Credits Reported privately by Ryan Vonbrubeck ([@dodge1218](https://github.com/dodge1218)).
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | @zenalexa/unicli (npm) | before 0.225.2 | 0.225.2 | Patch available | GHSA-v3f4-w7r7-v3hm |
- @zenalexa/unicli (npm) Vendor— Affected before 0.225.2 Fixed in 0.225.2 Patch available GHSA-v3f4-w7r7-v3hm
Remediation
- Fix · GHSA-v3f4-w7r7-v3hm @zenalexa/unicli (npm) Fixed in 0.225.2 Advisory →
Timeline
- 2026-10-03 Threatist record created from GHSA-v3f4-w7r7-v3hm
References
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences