CVE-2025-59956

6.5 MEDIUM
Published: September 30, 2025 Modified: October 08, 2025

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/coder/agentapi/pull/49
Source: security-advisories@github.com
Issue Tracking Patch
https://github.com/coder/agentapi/releases/tag/v0.4.0
Source: security-advisories@github.com
Release Notes
https://github.com/coder/agentapi/security/advisories/GHSA-w64r-2g3w-w8w4
Source: security-advisories@github.com
Patch Vendor Advisory
https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration
Source: security-advisories@github.com
Exploit Third Party Advisory
https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration/
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Exploit Third Party Advisory

7 reference(s) from NVD

Quick Stats

CVSS v3 Score
6.5 / 10.0
EPSS (Exploit Probability)
0.1%
19th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

coder