CVE-2026-46555
HighCVSS 7.7Exploitation Probability (EPSS)
Low risk9th percentile - higher than 9% of all known CVEs
Summary
WhatsApp MCP Server before version 0.2.1 has critical vulnerabilities: unauthenticated HTTP API on port 8080, missing Host header validation, and an absolute `media_path` parameter in the `/api/send` endpoint. This allows local processes to send WhatsApp messages and steal files, and remote attackers to exploit DNS rebinding.
Risk Assessment
The organization risks exposure of sensitive data (SSH keys, browser sessions, source code) and unauthorized sending of WhatsApp messages from the user's account. Attack can be carried out by malicious local processes or remotely via DNS rebinding.
Recommendation
Upgrade immediately to version 0.2.1, which introduces bearer token authentication, Host header allow-list, and path confinement. If upgrade is not possible, stop the bridge or block port 8080, avoid running alongside untrusted processes and browsing untrusted sites.
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Original NVD description (English source)
WhatsApp MCP Server is a Model Context Protocol (MCP) server for WhatsApp, enabling Claude to read and send WhatsApp messages. Prior to version 0.2.1, the `whatsapp-bridge` HTTP API listens on `127.0.0.1:8080` without authentication and without Host header validation, and the `/api/send` endpoint accepts an absolute `media_path` parameter without confining it to a safe directory. Combined, these issues allow any local process running as the same user as the bridge to send WhatsApp messages from the paired account without authorization; the same caller to read arbitrary files readable by the user (e.g. SSH private keys, browser session data, source code, dotfiles) and exfiltrate them as WhatsApp document attachments; and/or a remote attacker to trigger the same operations via DNS rebinding from a webpage the user visits, since no Host header validation is performed. In MCP environments, "local caller" extends beyond processes the user explicitly launched — sibling MCP servers, IDE extensions, and tool-triggered flows running in the user's session can act as the effective caller. This issue is fixed in whatsapp-mcp v0.2.1 and corresponding Docker images / release artifacts. Users should upgrade immediately. The fix introduces bearer token authentication on the bridge HTTP API (configured via environment variable, required on all requests, validated with constant-time comparison); host header allow-list validation to prevent DNS rebinding; and confinement of `media_path` to a configured directory, with rejection of absolute paths outside the root and path traversal sequences. This is a breaking change for clients of the bridge API. For users who cannot immediately upgrade: Stop the bridge, or block loopback access to port 8080, when the bridge is not actively in use; avoid running the bridge alongside untrusted MCP servers, browser extensions, or other untrusted local processes; avoid browsing untrusted sites while the bridge is running (DNS rebinding mitigation); and/or run the bridge under a dedicated user account or in a sandbox/container with no access to sensitive files.