Is there a public exploit for CVE-2026-123272?

No public exploit for CVE-2026-123272 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-123272?

CVE-2026-123272 scores CVSS 5.1 (v4.0), rated medium.

What does CVE-2026-123272 affect?

CVE-2026-123272 affects mark3labs mcp-go. It is part of the AI and agent stack (Model Context Protocol).

5.1 Medium

Mark3labs mcp-go before v1.2.1 contains an improper validation vulnerability in OAuthHandler.fetchServerMetadata that allows malicious MCP…

CVE-2026-123272

Mark3labs mcp-go before v1.2.1 contains an improper validation vulnerability in OAuthHandler.fetchServerMetadata that allows malicious MCP servers to obtain tokens for other resources by declaring arbitrary resources in well-known metadata. Attackers can declare a different MCP server as the RFC 8707 resource indicator, causing the authorization server to mint tokens the attacker replays against that resource.

Part of the AI stack

This affects Model Context Protocol, in MCP & tool servers.

Assessment

CVSS: 5.1 (v4.0)
Severity: Medium
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 5 November 2026
Last updated: 5 November 2026
Affected: mark3labs · mcp-go
Assigner: VulnCheck

CVSS vectorCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

At the source

EUVD (ENISA)

References

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Query this programmatically

Agents can read this through the MCP endpoint, or over HTTP:

curl https://cve.zerocrew.in/api/cve/CVE-2026-123272