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CVE-2026-123271ChatCLI before v1.215.2 Origin Validation Error via Unvalidated MCP OAuth Resource Indicator
ChatCLI before v1.215.2 contains an improper validation vulnerability in the MCP OAuth login flow that uses server-supplied Protected Resource Metadata as the resource indicator without checking it matches the configured server URL. A malicious MCP server can declare another resource on the same authorization server, obtain the user's bearer token for it, and replay that token against the other resource.
5.1 MEDIUMEPSS 0.14%Not in KEVNVD: Received
Overview
Severity
| Score | Severity | Version | Vector String |
|---|---|---|---|
| 5.1 | MEDIUM | 4.0VulnCheck (CNA) | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N |
| 8.0 | HIGH | 3.1VulnCheck (CNA) | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N |
Details
- CVE ID
- CVE-2026-123271
- Status
- Received
- Assigner (CNA)
- VulnCheck
- Published
- Nov 5, 2026
- Last modified
- 2026-11-05 19:17 UTC
- Weaknesses
- CWE-346 · Origin Validation Error
Affected Products
As published by the CNA in the CVE record.
diillsonChatCLI1 version range
- v1.159.0 before v1.215.2
References
- github.com https://github.com/diillson/chatcli/blob/359eb27debc4de78289a9662551a51ab4528e16c/cli/mcp/oauth.go#L477-L493
- github.com https://github.com/diillson/chatcli/commit/951fe24b8e090eae86bf8edb13a788916b1e6c91
- github.com https://github.com/diillson/chatcli/releases/tag/v1.215.2
- github.com https://github.com/diillson/chatcli/security/advisories/GHSA-95vg-3r9c-2v5q
- vulncheck.com https://www.vulncheck.com/advisories/chatcli-before-1.215.2-origin-validation-error-via-unvalidated-mcp-oauth-resource-indicator