Vulnerability · Published Sep 29, 2025 · Assigned by GitHub_M
CVE-2025-59956AgentAPI exposed user chat history via a DNS rebinding attack
Medium 6.5
In plain English
A medium-severity security flaw in agentapi from coder. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
AgentAPI is an HTTP API for Claude Code, Goose, Aider, Gemini, Amp, and Codex. Versions 0.3.3 and below are susceptible to a client-side DNS rebinding attack when hosted over plain HTTP on localhost. An attacker can gain access to the /messages endpoint served by the Agent API. This allows for the unauthorized exfiltration of sensitive user data, specifically local message history, which can include secret keys, file system contents, and intellectual property the user was working on locally. This issue is fixed in version 0.4.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/coder/agentapi | 0.4.0 | GHSA-w64r-2g3w-w8w4 |
| Go | github.com/coder/agentapi | 0.4.0 | GO-2025-3991 |
Affected products (as reported)
Weakness: CWE-350 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
References
- https://github.com/coder/agentapi/security/advisories/GHSA-w64r-2g3w-w8w4 x_refsource_CONFIRM
- https://github.com/coder/agentapi/pull/49 x_refsource_MISC
- https://github.com/coder/agentapi/commit/5c425c62447b8a9eac19e9fc5a2eae7f0803f149 x_refsource_MISC
- https://github.blog/security/application-security/localhost-dangers-cors-and-dns-rebinding x_refsource_MISC
- https://github.com/coder/agentapi/releases/tag/v0.4.0 x_refsource_MISC
- https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration x_refsource_MISC
- https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration/ exploit