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TI-2026-85605 Aliases CVE-2026-123271GHSA-2gm2-hpg7-78f2

Origin validation flaw in ChatCLI MCP OAuth login exposes tokens

Priority LOW 22CWE-346Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Active
Attack complexity
Low
Attack requirements
Present
Impact type
Security bypass
Confidentiality · integrity · availability
None · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-346.

Summary

ChatCLI from v1.159.0 before v1.215.2 is affected. Its MCP OAuth login flow uses server-supplied Protected Resource Metadata as the resource indicator without checking it against the configured server URL, an origin validation error (CWE-346). 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 that other resource.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

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.

Why it matters now

EPSS 0.00146 3rd percentileScored 2026-11-07
Fix Fixed ChatCLI (diillson): v1.215.2

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
diillsonChatCLIv1.159.0 to before v1.215.2v1.215.2Patch availableCNA
  • ChatCLI Vendordiillson Affected v1.159.0 to before v1.215.2 Fixed in v1.215.2 Patch available CNA

Remediation

Upgrade ChatCLI to v1.215.2, the fixed version.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

  • Fix · CNA ChatCLI (diillson) Fixed in v1.215.2

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-11-05 Threatist record created from CVE-2026-123271
  2. 2026-11-05 Alias added: GHSA-2gm2-hpg7-78f2
  3. 2026-11-06 Affected versions changed · Red Hat
  4. 2026-11-06 CVSS score added · Red Hat

References

Patch 1

Advisory 1

Other 2

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences