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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| coder | agentapi | < 0.4.0 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP6 | govulncheck-vulndb | 0.0.20251023T162509-150000.1.110.1 | SUSE-SU-2025:3799-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | govulncheck-vulndb | 0.0.20251023T162509-1.1 | openSUSE-SU-2025:15666-1 |
| openSUSE Leap 16.0 | govulncheck-vulndb | 0.0.20260723T184607-160000.1.1 | openSUSE-SU-2026:21483-1 |
| openSUSE Leap 15.6 | govulncheck-vulndb | 0.0.20251023T162509-150000.1.110.1 | SUSE-SU-2025:3799-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/coder/agentapi | < 0.4.0 | 0.4.0 | GHSA-w64r-2g3w-w8w4 |
Advisories 3
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
- openSUSE-SU-2025:15666-1 govulncheck-vulndb-0.0.20251023T162509-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:3799-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Feb 4, 2026
References
- https://github.com/coder/agentapi/security/advisories/GHSA-w64r-2g3w-w8w4
- https://github.com/coder/agentapi/pull/49
- https://github.com/coder/agentapi/commit/5c425c62447b8a9eac19e9fc5a2eae7f0803f149
- https://github.blog/security/application-security/localhost-dangers-cors-and-dns-rebinding
- https://github.com/coder/agentapi/releases/tag/v0.4.0
- https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration