CVE-2026-123271

EUVD-2026-117724
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
8 HIGH
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Common Weakness Enumeration
References
https://github.com/diillson/chatcli/blob/359eb27debc4de78289a9662551a51ab4528e16c/cli/mcp/oauth.go#L477-L493
https://github.com/diillson/chatcli/commit/951fe24b8e090eae86bf8edb13a788916b1e6c91
https://github.com/diillson/chatcli/releases/tag/v1.215.2
https://github.com/diillson/chatcli/security/advisories/GHSA-95vg-3r9c-2v5q
https://www.vulncheck.com/advisories/chatcli-before-1.215.2-origin-validation-error-via-unvalidated-mcp-oauth-resource-indicator