CVE-20XX-?
agent?

CVE-2026-123272

5.1 MEDIUM 0.2% exploit odds Fix listed Disclosure Library

What it is

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.

At a glance

Exploitability
Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.
Exploit odds
0.2% chance of exploitation in the next 30 days (EPSS).
Fix
A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

  1. ReservedThe CVE id was reserved by its CNA
  2. PublishedDisclosed publicly on CVE.org and NVD
  3. Last updatedMost recent change to the record

Why it ranks here

Details

Published
Last modified
Exploit probability
0.2% · EPSS, next 30 days
Weakness
CWE-346
Record status
Deferred

Attack profile CVSS 4.0 · 5.1

Attack vector
Network
Complexity
Low
Attack requirements
Present
Privileges needed
None
User interaction
Active
Confidentiality
None
Integrity
None
Availability
None
Raw 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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-123272.md and follow it. Check whether this project is affected by CVE-2026-123272. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record