CVE-2025-59956
AgentAPI exposed user chat history via a DNS rebinding attack
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.
INFO
Published Date :
Sept. 30, 2025, 11:37 a.m.
Last Modified :
June 17, 2026, 9:46 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | MITRE-CVE | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update AgentAPI to version 0.4.0 or later.
- Host AgentAPI over HTTPS.
Public PoC/Exploit Available at Github
CVE-2025-59956 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-59956.
| URL | 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 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-59956 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-59956
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
The Project shares all information on MCP related CVE's published
mcp mcp-security mcp-cve
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-59956 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-59956 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'coder', 'product': 'agentapi', 'versions': [{'status': 'affected', 'version': '< 0.4.0'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2025-59956', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2025-09-30T14:14:39.407205Z'} -
Initial Analysis by [email protected]
Oct. 08, 2025
Action Type Old Value New Value Added CWE CWE-290 Added CPE Configuration OR *cpe:2.3:a:coder:agentapi:*:*:*:*:*:*:*:* versions up to (excluding) 0.4.0 Added Reference Type GitHub, Inc.: https://github.blog/security/application-security/localhost-dangers-cors-and-dns-rebinding Types: Technical Description Added Reference Type GitHub, Inc.: https://github.com/coder/agentapi/commit/5c425c62447b8a9eac19e9fc5a2eae7f0803f149 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/coder/agentapi/pull/49 Types: Issue Tracking, Patch Added Reference Type GitHub, Inc.: https://github.com/coder/agentapi/releases/tag/v0.4.0 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/coder/agentapi/security/advisories/GHSA-w64r-2g3w-w8w4 Types: Patch, Vendor Advisory Added Reference Type GitHub, Inc.: https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration Types: Exploit, Third Party Advisory Added Reference Type CISA-ADP: https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration/ Types: Exploit, Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 30, 2025
Action Type Old Value New Value Added Reference https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration/ -
New CVE Received by [email protected]
Sep. 30, 2025
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N Added CWE CWE-350 Added Reference https://github.blog/security/application-security/localhost-dangers-cors-and-dns-rebinding Added Reference https://github.com/coder/agentapi/commit/5c425c62447b8a9eac19e9fc5a2eae7f0803f149 Added Reference https://github.com/coder/agentapi/pull/49 Added Reference https://github.com/coder/agentapi/releases/tag/v0.4.0 Added Reference https://github.com/coder/agentapi/security/advisories/GHSA-w64r-2g3w-w8w4 Added Reference https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration