This vulnerability affects ag-ui-protocol's ag-ui version 1.0, specifically the prepareRunAgentInput function in the agent/agent.ts file of the Event Application Layer component. The issue arises from improper origin validation due to manipulation of the TEXT_MESSAGE_START argument, which can be exploited remotely. The vulnerability has a CVSS 4.0 base score of 5.3, indicating medium severity. Although a pull request containing a fix exists, it has not yet been accepted or officially released.

The vulnerability allows remote attackers to exploit an origin validation error, potentially leading to unauthorized actions or bypass of security controls related to origin checks. The CVSS vector indicates low complexity and no user interaction required, but limited privileges are needed. The impact includes limited confidentiality, integrity, and availability impacts. No known exploits are currently in the wild.

A fix for this vulnerability has been developed but is not yet officially released. Users should monitor the vendor's repository or advisory channels for the acceptance of the pull request and apply the official patch once available. Until then, no official mitigation or workaround is confirmed.