CVE-2025-59956

Name: CVE-2025-59956
Creator: NVD / NIST
Published: 2025-09-30T11:37:41.743+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.40%

Last modified Jun 17, 2026

CVE-2025-59956 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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. EPSS estimates a 0.40% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

EPSS Probability

0.40%

31.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Coder	Agentapi	< 0.4.0

References

https://github.blog/security/application-security/localhost-dangers-cors-and-dns-rebindingTechnical Description
https://github.com/coder/agentapi/commit/5c425c62447b8a9eac19e9fc5a2eae7f0803f149Patch
https://github.com/coder/agentapi/pull/49Issue Tracking, Patch
https://github.com/coder/agentapi/releases/tag/v0.4.0Release Notes
https://github.com/coder/agentapi/security/advisories/GHSA-w64r-2g3w-w8w4Patch, Vendor Advisory
https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltrationExploit, Third Party Advisory
https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration/Exploit, Third Party Advisory

Timeline

Published: Sep 30, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2025-59956?

How severe is CVE-2025-59956?

CVE-2025-59956 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.40% probability of exploitation in the next 30 days.

How do I fix CVE-2025-59956?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-59956?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST