{"id":"CVE-2026-123271","aliases":["EUVD-2026-117724","GHSA-2gm2-hpg7-78f2","GHSA-95vg-3r9c-2v5q"],"status":"published","title":"ChatCLI before v1.215.2 Origin Validation Error via Unvalidated MCP OAuth Resource Indicator","description":"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.","severity":{"version":"4.0","score":5.1,"vector":"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00146,"percentile":0.03926,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-346"],"published":"2026-11-05T18:45:35Z","modified":"2026-11-06T10:46:43Z","products":[{"vendor":"diillson","product":"chatcli"}],"references":[{"url":"https://github.com/diillson/chatcli/security/advisories/GHSA-95vg-3r9c-2v5q","tags":["vendor-advisory","advisory"]},{"url":"https://github.com/diillson/chatcli/commit/951fe24b8e090eae86bf8edb13a788916b1e6c91","tags":["patch","fix"]},{"url":"https://github.com/diillson/chatcli/releases/tag/v1.215.2","tags":["release-notes","advisory"]},{"url":"https://github.com/diillson/chatcli/blob/359eb27debc4de78289a9662551a51ab4528e16c/cli/mcp/oauth.go#L477-L493","tags":["technical-description","article"]},{"url":"https://www.vulncheck.com/advisories/chatcli-before-1.215.2-origin-validation-error-via-unvalidated-mcp-oauth-resource-indicator","tags":["third-party-advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123271","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-2gm2-hpg7-78f2"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/123xxx/CVE-2026-123271.json","tags":["advisory"]},{"url":"https://github.com/diillson/chatcli","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-123271","title":"ChatCLI before v1.215.2 Origin Validation Error via Unvalidated MCP OAuth Resource Indicator","description":"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.","status":"published","published":"2026-11-05T18:45:35.481Z","modified":"2026-11-09T17:44:06.128Z","cvss":[{"version":"4.0","score":5.1,"vector":"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","level":"medium","assessor":"cna"},{"version":"3.1","score":8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-346"],"updated_at":"2026-11-08T15:43:32.737211Z"}],"euvd":[{"id":"EUVD-2026-117724","description":"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.","status":"published","published":"2026-11-05T18:45:35Z","modified":"2026-11-09T17:44:06Z","cvss":[{"version":"4.0","score":5.1,"vector":"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","level":"medium"}],"updated_at":"2026-11-08T15:13:09.785497Z"}],"ghsa":[{"id":"GHSA-2gm2-hpg7-78f2","title":"ChatCLI before v1.215.2 contains an improper validation vulnerability in the MCP OAuth login flow...","description":"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.","status":"published","published":"2026-11-05T21:34:51Z","modified":"2026-11-05T21:35:00Z","cvss":[{"version":"4.0","score":5.1,"vector":"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/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","level":"medium"},{"version":"3.1","score":8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-346"],"updated_at":"2026-11-05T21:56:38.142385Z"}],"nvd":[{"id":"CVE-2026-123271","description":"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.","status":"published","published":"2026-11-05T19:17:20.543Z","modified":"2026-11-09T18:17:25.39Z","cvss":[{"version":"4.0","score":5.1,"vector":"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/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","level":"medium","assessor":"secondary"},{"version":"3.1","score":8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-346"],"updated_at":"2026-11-08T16:10:21.004208Z"}],"osv":[{"id":"CVE-2026-123271","title":"ChatCLI before v1.215.2 Origin Validation Error via Unvalidated MCP OAuth Resource Indicator","description":"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.","status":"published","published":"2026-11-05T18:45:35.481Z","modified":"2026-11-11T02:30:34.922184609Z","cvss":[{"version":"4.0","score":5.1,"vector":"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","level":"medium"}],"cwes":["CWE-346"],"updated_at":"2026-11-07T03:08:01.726202Z"}]}}