CVE-2026-123271— ChatCLI before v1.215.2 Origin Validation Error via Unvalidated MCP OAuth Resource Indicator

Quick assessment

Affected

diillson ChatCLI

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

ChatCLI 在 v1.215.2 之前的版本中，其 MCP OAuth 登录流程存在不当验证漏洞：该流程将服务器提供的受保护资源元数据（Protected Resource Metadata）直接用作资源标识符，却未验证其是否与已配置的服务器 URL 匹配。攻击者可利用此漏洞，通过恶意的 MCP 服务器声明同一授权服务器下的其他资源，从而获取用户针对该资源的访问令牌（Bearer Token），并将该令牌重放至其他资源以进行未授权访问。

CVSS 8.0 · High Updated Nov 06, 2026

Possible ATT&CK Techniques 2 AI

T1078 · Valid Accounts T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

Vendor	Product	Version Range	Status
diillson	ChatCLI	`v1.159.0< v1.215.2`	affected

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Vulnerability Information

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Vulnerability Title

ChatCLI before v1.215.2 Origin Validation Error via Unvalidated MCP OAuth Resource Indicator

Source: CVE Program / CVE List V5

Vulnerability 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.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N

Source: CVE Program / CVE List V5

Vulnerability Type

源验证错误

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
diillson	ChatCLI	v1.159.0 ~ v1.215.2	-

II. Public POCs for CVE-2026-123271

#	POC Description	Source Link	Shenlong Link

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No public POC found.

III. Intelligence Information for CVE-2026-123271

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Other References for CVE-2026-123271 (5)

https://github.com/diillson/chatcli/blob/359eb27debc4de78289a9662551a51ab4528e16c/cli/mcp/oauth.go#L477-L493 technical-description
https://github.com/diillson/chatcli/commit/951fe24b8e090eae86bf8edb13a788916b1e6c91 patch
https://github.com/diillson/chatcli/releases/tag/v1.215.2 release-notes
https://github.com/diillson/chatcli/security/advisories/GHSA-95vg-3r9c-2v5q vendor-advisory
https://www.vulncheck.com/advisories/chatcli-before-1.215.2-origin-validation-error-via-unvalidated-mcp-oauth-resource-indicator third-party-advisory

https://www.cve.org/CVERecord?id=CVE-2026-123271

IV. Related Vulnerabilities

Same weakness: CWE-346