GHSA-w64r-2g3w-w8w4

Coder AgentAPI exposed user chat history via a DNS rebinding attack

Source: GitHub Advisory Database (reviewed) Moderate CVE-2025-59956

Packages

Ecosystem	Package	Affected	Fixed in
Go	github.com/coder/agentapi	< 0.4.0	0.4.0

Details

As written in the advisory (Markdown source, shown as plain text).

### Summary AgentAPI prior to version [0.4.0](https://github.com/coder/agentapi/releases/tag/v0.4.0) was susceptible to a client-side DNS rebinding attack when hosted over plain HTTP on localhost. ### Impact An attacker could have gained access to the `/messages` endpoint served by the Agent API. This allowed for the unauthorized exfiltration of sensitive user data, specifically local message history, which could've included secret keys, file system contents, and intellectual property the user was working on locally. ### Remediation We've [implemented](https://github.com/coder/agentapi/pull/49) an `Origin` and `Host` header validating middleware and set a secure by default configuration. Please upgrade to version [0.4.0](https://github.com/coder/agentapi/releases/tag/v0.4.0) or later. ### Credits We'd like to thank [Evan Harris](https://github.com/eharris128) from [mcpsec.dev](https://mcpsec.dev/) for reporting this issue and following the coordinated disclosure [policy](https://coder.com/security/policy).

References

External links from the advisory. They lead to third-party sites.