CVE-2026-58497

Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests

HIGH

8.6

CVSS Score

Published: October 23, 2026 at 02:49 PM UTC

Updated: October 23, 2026 at 09:17 PM UTC

1 product affected across 1 vendorUni-CLI

Using Uni-CLI by olo-dot-io?

Get instant alerts when new vulnerabilities affect Uni-CLI - before attackers find them.

Real-time alertsTrack your software stackFree plan available

Start Free Sign In

Severity

HIGH8.6

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

Description

Uni-CLI gives people and agents one command interface for websites, browsers, desktop applications, local tools, and MCP. Prior to version 0.225.2, Uni-CLI 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. This issue has been patched in version 0.225.2.