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No exploitation reportedAwaiting NVD analysis

CVE-2026-123271

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

No exploitation reported by the sources we read.

  • Published2026-11-05
  • WeaknessCWE-346

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-11-0518:45CVE publishedCNA

Versions per branch

Products declared by the CNA

As VulnCheck, the CNA that assigned this CVE, declared them in the CVE record; versions as written. NVD lists no product for this CVE yet: this is the only product data so far.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-05

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-123271 yet.

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Metasploit modules
none listed
Metasploit Framework

Sources

  • CNACVSS 4.05.12026-11-05
  • CNACVSS 3.182026-11-05
  • NVDCVSS 3.18read 2026-11-05
  • CNAweakness (CWE)CWE-3462026-11-05
  • NVDweakness (CWE)CWE-346read 2026-11-05

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
CVSS 4.0 vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
2026-11-05
Last Modified
2026-11-05
NVD status
Received

Frequently asked questions

What is CVE-2026-123271?

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.

Is CVE-2026-123271 actively exploited?

Active exploitation of CVE-2026-123271 has not been confirmed.

What is the CVSS score for CVE-2026-123271?

CVE-2026-123271 has a CVSS v3 base score of 8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N.

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