CVE-2026-58497
Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Passive
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests
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.
- Record
CVE-2026-58497- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N - Weakness
- CWE-346, CWE-352
- Updated
- 2026-11-02
EUVDEUVD-2026-109090
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.
- Record
EUVD-2026-109090- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-v3f4-w7r7-v3hm
Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests
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).
- Record
GHSA-v3f4-w7r7-v3hm- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N - Weakness
- CWE-346, CWE-352
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-58497- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/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 - Weakness
- CWE-346, CWE-352
- Updated
- 2026-11-02
OSV
Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests
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.
- Record
CVE-2026-58497- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N - Weakness
- CWE-346, CWE-352
- Updated
- 2026-11-02
OSVGHSA-v3f4-w7r7-v3hm
Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests
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).
- Record
GHSA-v3f4-w7r7-v3hm- CVSS 4.0
- 8.6 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N - Weakness
- CWE-346, CWE-352
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
@zenalexa/uniclinpm |
before 0.225.2 | 0.225.2 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-58497 is a high vulnerability (CVSS 8.6) in Olo-dot-io Uni-cli, published June 19, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.26%, the 17th percentile. Fixed in @zenalexa/unicli 0.225.2.
References
github.com/olo-dot-io/Uni-CLI/security/advisories/GHSA-v3f4-w7r7-v3hm
nvd.nist.gov/vuln/detail/CVE-2026-58497