CVE-2026-123271 ChatCLI before v1.215.2 Origin Validation Error via Unvalidated MCP OAuth Resource Indicator
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-123271?
CVE-2026-123271 is a medium-severity vulnerability in diillson ChatCLI, published on 5 Nov 2026.
Official 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.
Weakness: CWE-346
Which versions are affected by CVE-2026-123271?
How do I fix CVE-2026-123271?
No fix has been published for CVE-2026-123271 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-123271 being exploited?
There is no known exploitation of CVE-2026-123271 in the wild and no public exploit code.
Sources
Also known as GHSA-2gm2-hpg7-78f2, GHSA-95vg-3r9c-2v5q.