{"id":"CVE-2026-123271","aliases":["GHSA-95vg-3r9c-2v5q"],"url":"https://o3.security/vulnerability/CVE-2026-123271","summary":"ChatCLI before v1.215.2 Origin Validation Error via Unvalidated MCP OAuth Resource Indicator","details":"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.","published":"2026-11-05T18:45:35.481Z","modified":"2026-11-06T10:46:43.139333948Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":{"url":"https://github.com/diillson/chatcli/commit/951fe24b8e090eae86bf8edb13a788916b1e6c91","label":"diillson/chatcli@951fe24"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/123xxx/CVE-2026-123271.json"},{"type":"PACKAGE","url":"https://github.com/diillson/chatcli"},{"type":"ARTICLE","url":"https://github.com/diillson/chatcli/blob/359eb27debc4de78289a9662551a51ab4528e16c/cli/mcp/oauth.go#L477-L493"},{"type":"FIX","url":"https://github.com/diillson/chatcli/commit/951fe24b8e090eae86bf8edb13a788916b1e6c91"},{"type":"ADVISORY","url":"https://github.com/diillson/chatcli/releases/tag/v1.215.2"},{"type":"ADVISORY","url":"https://github.com/diillson/chatcli/security/advisories/GHSA-95vg-3r9c-2v5q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123271"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/chatcli-before-1.215.2-origin-validation-error-via-unvalidated-mcp-oauth-resource-indicator"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-11-06T10:46:43.139333948Z"}}