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CVE-2023-46729 is a critical Server-Side Request Forgery vulnerability present in the Sentry JavaScript SDK for Next.js.
Specifically, applications utilizing the Next.js SDK tunneling feature within versions 7.26.0 through 7.76.0 are affected.
The vulnerability arises because the SDK’s tunnel endpoint uses unsanitized input parameters for proxying requests.
When configuring the `tunnelRoute` option, the framework creates a Next.js rewrite target using query parameters.
Attackers can manipulate the organization ID and project ID query parameters sent to the tunnel endpoint.
Because the regular expression patterns validating these parameters were overly permissive, they failed.
Instead of restricting input to expected formats, the endpoint allowed arbitrary URL components to be injected.
Consequently, an external attacker can send crafted HTTP requests targeting internal infrastructure through the server.
The vulnerable Next.js application acts as a proxy, executing requests against internal services otherwise protected by a firewall.
Furthermore, the response from the internal service or external target is reflected back to the attacker’s client.
This enables malicious actors to perform port scanning, retrieve internal metadata, or exfiltrate sensitive data.
Exploitation requires network access to the application endpoint and relies on the tunneling feature being actively enabled.
Developers who omitted or disabled the tunneling feature remain completely safe from this specific attack vector.
Mitigation requires upgrading the `@sentry/nextjs` package to version 7.77.0 or later where strict validation is enforced.
The official patch introduces strict regular expression checks ensuring organization IDs contain only valid characters.
Similarly, project identifiers are restricted strictly to numeric digits to prevent path traversal or parameter injection.
If upgrading immediately is not feasible, administrators can temporarily remove or undefined the `tunnelRoute` configuration option.
Security analysts recommend auditing application access logs for abnormal query parameters containing non-standard characters.
Network monitoring tools should also inspect outbound traffic patterns originating from Next.js application servers for anomalies.
DailyCVE Form:
Platform: Sentry Next.js SDK
Version: 7.26.0 to 7.76.0
Vulnerability: Server Side Forgery
Severity: Critical
date: November 9 2023
Prediction: Patched On Time
What Undercode Say:
The vulnerability highlights the risks of improper input validation within proxy and tunneling features. Developers often trust internal routing parameters implicitly, assuming they originate from trusted SDK controls. However, exposing rewrite mechanisms directly to user-supplied query parameters without strict regex validation breaks boundary assumptions. Security teams must treat all parameters handling routing logic as completely untrusted input.
Bash commands and codes
npm install @sentry/[email protected]
// Vulnerable configuration example
Sentry.init({
dsn: "YOUR_DSN",
tunnelRoute: "/monitoring"
});
curl -i "https://vulnerable-app.com/monitoring?o=../../&p=internal-service"
Exploit: (Educational Purposes!)
The exploit involves sending an HTTP GET request to the Sentry tunnel endpoint with malicious parameters. An attacker crafts a request where the organization or project parameter contains arbitrary URL components or traversal sequences. The Next.js server interprets these parameters and forwards an outbound request to an internal target or arbitrary external URL. The response from the internal resource is then captured and reflected in the HTTP response body returned to the attacker.
Protection: from this CVE
To protect applications from CVE-2023-46729, immediately upgrade the Sentry Next.js SDK to version 7.77.0 or higher. If updating packages is not immediately possible, disable the SDK tunneling feature by removing the `tunnelRoute` parameter from your configuration file. Implement strict egress filtering and network segmentation on your application servers to block unauthorized internal requests. Monitor access logs for suspicious query parameters targeting the telemetry endpoint.
Impact:
Successful exploitation of this vulnerability allows unauthorized external actors to interact with internal network resources. Attackers can perform internal port scanning, access sensitive internal metadata services, and exfiltrate confidential data. In certain scenarios, the vulnerable server can be abused as a proxy to launch secondary attacks against other internal systems while masking the attacker’s true origin.
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Sources:
Reported By: github.com
Extra Source Hub:
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