---
id: CVE-2026-123271
title: >-
  ChatCLI before v1.215.2 Origin Validation Error via Unvalidated MCP OAuth
  Resource Indicator
summary: >-
  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 ma…
severity: high
cvss: 8
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N'
cvssSource: cna
cwe:
  - CWE-346
vendor: diillson
product: ChatCLI
affected:
  - ChatCLI >= v1.159.0 < v1.215.2
published: '2026-11-05'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T18:45:35.481Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-123271'
references:
  - url: >-
      https://github.com/diillson/chatcli/security/advisories/GHSA-95vg-3r9c-2v5q
    label: GitHub Security Advisory (GHSA-95vg-3r9c-2v5q)
  - url: >-
      https://github.com/diillson/chatcli/commit/951fe24b8e090eae86bf8edb13a788916b1e6c91
  - url: 'https://github.com/diillson/chatcli/releases/tag/v1.215.2'
    label: ChatCLI v1.215.2 Release Notes
  - url: >-
      https://github.com/diillson/chatcli/blob/359eb27debc4de78289a9662551a51ab4528e16c/cli/mcp/oauth.go#L477-L493
  - url: >-
      https://www.vulncheck.com/advisories/chatcli-before-1.215.2-origin-validation-error-via-unvalidated-mcp-oauth-resource-indicator
    label: >-
      VulnCheck Advisory: ChatCLI before v1.215.2 Origin Validation Error via
      Unvalidated MCP OAuth Resource Indicator
tags:
  - cve.org
ingestedAt: '2026-11-05T22:38:31.479Z'
---

## Overview

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.

## Affected

- `ChatCLI >= v1.159.0 < v1.215.2`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.