CVE-2025-59956

AgentAPI exposed user chat history via a DNS rebinding attack

MEDIUM
6.5
CVSS Score
Published: September 29, 2025 at 11:57 PM UTC
Updated: June 17, 2026 at 09:46 AM UTC
1 product affected across 1 vendorAgentAPI

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.4%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.4.0
Affected range stops below 0.4.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (7)

x_refsource_CONFIRMPatchVendor Advisory
Source: cverecord
https://github.com/coder/agentapi/security/advisories/GHSA-w64r-2g3w-w8w4
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/coder/agentapi/pull/49
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/coder/agentapi/releases/tag/v0.4.0
x_refsource_MISCExploitThird Party Advisory
Source: cverecord
https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration
ExploitThird Party Advisory
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://mcpsec.dev/advisories/2025-09-19-coder-chat-exfiltration/

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-350CWE-290

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