CVE-2026-19340 Overview
CVE-2026-19340 is a server-side request forgery (SSRF) vulnerability affecting anubissbe ProjectHub-Mcp versions up to 5.0.0. The flaw resides in the Webhooks API component, specifically in an unknown function within the backend-fix/complete_backend.js file. An authenticated remote attacker can manipulate the url argument to coerce the server into issuing arbitrary outbound HTTP requests. The maintainer was notified through a public issue report but has not yet responded. The vulnerability is classified under CWE-918: Server-Side Request Forgery.
Critical Impact
Remote authenticated attackers can abuse the Webhooks API to send crafted requests from the ProjectHub-Mcp server to internal or external targets, enabling reconnaissance and interaction with services otherwise unreachable.
Affected Products
- anubissbe ProjectHub-Mcp versions up to and including 5.0.0
- Component: Webhooks API (backend-fix/complete_backend.js)
- Vulnerable parameter: url
Discovery Timeline
- 2026-08-09 - CVE-2026-19340 published to NVD
- 2026-08-13 - Last updated in NVD database
Technical Details for CVE-2026-19340
Vulnerability Analysis
The vulnerability lives in the Webhooks API handler in backend-fix/complete_backend.js. The endpoint accepts a user-controlled url argument and passes it to a server-side HTTP client without adequate validation of the destination. As a result, the server acts as a proxy for attacker-directed requests. An attacker with low-privileged access can point the webhook at internal endpoints, cloud metadata services, or third-party APIs. The response, redirect behavior, or timing side channels can leak information about the internal network. The advisory does not indicate authenticated access to internal admin functions, but SSRF frequently chains with metadata service abuse to escalate impact. The maintainer has not published a fix, which extends the exposure window for downstream deployments.
Root Cause
The root cause is missing validation and allow-listing on the webhook url parameter. The application does not enforce restrictions on scheme, host, or IP range before dispatching the outbound HTTP request. Requests to private address space, loopback, and link-local metadata endpoints are not blocked.
Attack Vector
Exploitation is remote and requires network access to the Webhooks API along with low-privileged credentials. The attacker submits a webhook configuration or invocation containing a crafted url value referencing an internal resource. The ProjectHub-Mcp backend then issues the request from its own network position. No user interaction is required. See the GitHub issue tracking this vulnerability and the VulDB entry for CVE-2026-19340 for additional technical context.
No verified public exploit code is available. The vulnerability mechanism is described in prose only.
Detection Methods for CVE-2026-19340
Indicators of Compromise
- Outbound HTTP requests from the ProjectHub-Mcp host to RFC1918 addresses, 127.0.0.1, 169.254.169.254, or other cloud metadata endpoints
- Webhook configurations containing non-standard schemes such as file://, gopher://, or internal hostnames
- Unexpected spikes in webhook invocations targeting unique destinations from the same authenticated account
Detection Strategies
- Inspect application logs for webhook creation and invocation events, correlating the submitted url field against an allow-list of intended integration domains
- Deploy an egress proxy in front of the ProjectHub-Mcp backend and alert on requests to private, loopback, or metadata IP ranges
- Review the backend-fix/complete_backend.js code path handling webhook url inputs to confirm whether protocol and destination filtering is present
Monitoring Recommendations
- Enable verbose logging of outbound HTTP calls made by the ProjectHub-Mcp process, including destination IP, port, and response codes
- Forward webhook API access logs to a centralized analytics platform for anomaly detection on parameter values
- Establish network baselines for the application host so that new destinations trigger review
How to Mitigate CVE-2026-19340
Immediate Actions Required
- Restrict network egress from the ProjectHub-Mcp server to only the destinations required for legitimate webhook delivery
- Block outbound access from the application host to cloud metadata endpoints such as 169.254.169.254 and to internal management interfaces
- Revoke or rotate any credentials or tokens that were reachable from the ProjectHub-Mcp host, since SSRF can expose them
- Limit which user roles can create or modify webhook configurations
Patch Information
No vendor patch is available at the time of publication. The project was informed of the issue via a public issue report but has not responded. Track the GitHub project repository and issue #176 for remediation updates.
Workarounds
- Place the application behind an authenticated forward proxy that enforces a destination allow-list for outbound webhook traffic
- Reject webhook URLs that resolve to private, loopback, link-local, or reserved IP ranges before making the request
- Enforce https:// scheme only and disable following of HTTP redirects into disallowed ranges
- Deploy web application firewall rules that inspect the url parameter submitted to the Webhooks API and drop suspicious values
# Example egress restriction using iptables to block metadata service access
iptables -A OUTPUT -d 169.254.169.254 -j DROP
iptables -A OUTPUT -d 127.0.0.0/8 ! -o lo -j DROP
iptables -A OUTPUT -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
