# CVE-2025-59956: AgentAPI exposed user chat history via a DNS rebinding attack

> Attackers can exfiltrate sensitive local chat history and secrets from AgentAPI via DNS rebinding when hosted on plain HTTP localhost.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 29 Sep 2025
- **Updated:** 30 Sep 2025
- **Also known as:** GHSA-w64r-2g3w-w8w4, GO-2025-3991

## What is CVE-2025-59956?

CVE-2025-59956 is a medium-severity server-side request forgery vulnerability in coder agentapi, published on 29 Sep 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### 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.

Weakness: CWE-290 (Authentication Bypass by Spoofing), CWE-350 (Reliance on Reverse DNS Resolution for a Security-Critical Action)

## Which versions are affected by CVE-2025-59956?

3 open source packages ship an affected version, including github.com/coder/agentapi. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/coder/agentapi` | Go | All versions | 0.4.0 |
| `github.com/coder/agentapi` | Go | All versions | 0.4.0 |
| `github.com/coder/agentapi` | Go | All versions | 0.4.0 |

Products: Coder Agentapi.

## How do I fix CVE-2025-59956?

Upgrade github.com/coder/agentapi to 0.4.0 or later.

## Is CVE-2025-59956 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-59956 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-59956 and fix it if it is affected.

What it is: CVE-2025-59956 is a medium-severity server-side request forgery vulnerability in coder agentapi, published on 29 Sep 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-59956 exists.

Affected packages and fixed versions:
- github.com/coder/agentapi (Go): affected all versions; fixed in 0.4.0
- github.com/coder/agentapi (Go): affected all versions; fixed in 0.4.0
- github.com/coder/agentapi (Go): affected all versions; fixed in 0.4.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-59956/ (Markdown: https://insights.sbomify.com/CVE-2025-59956/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-59956
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-59956
- OSV: https://osv.dev/vulnerability/CVE-2025-59956

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-59956/
Summaries are generated and may contain mistakes; the official description above is the record.