CVE-2025-59956

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.

CVSS v3 6.5 MEDIUM

6.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.blog/security/application-security/localhost-dangers-cors-and-dns-rebinding	Technical Description
https://github.com/coder/agentapi/commit/5c425c62447b8a9eac19e9fc5a2eae7f0803f149	Patch
https://github.com/coder/agentapi/pull/49	Issue Tracking Patch
https://github.com/coder/agentapi/releases/tag/v0.4.0	Release Notes
https://github.com/coder/agentapi/security/advisories/GHSA-w64r-2g3w-w8w4	Patch Vendor Advisory
https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration	Exploit Third Party Advisory
https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration/	Exploit Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:coder:agentapi:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2025-09-30 11:37

Updated : 2025-10-08 15:05

NVD link : CVE-2025-59956

Mitre link : CVE-2025-59956

CVE.ORG link : CVE-2025-59956

JSON object : View

Products Affected

coder

agentapi

CWE

CWE-350

Reliance on Reverse DNS Resolution for a Security-Critical Action

CWE-290

Authentication Bypass by Spoofing

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