Quasar Framework SSR/SSG Development Server Information Disclosure and HTML Injection

The Quasar Framework development server, used in SSR and SSG modes, contains a critical information disclosure vulnerability (CVE-2026-106106) in the renderSSRError utility. When a rendering exception occurs during development, the framework serializes sensitive data including the full shell environment (process.env), all request headers, and all cookies into an HTTP 500 error page. Because the Quasar CLI overrides the Vite default localhost binding to listen on 0.0.0.0, this sensitive information is exposed to any network host capable of reaching the development port.

Furthermore, the error page embeds this serialized data within a <script> element using a flawed string replacement routine (replaceAll('</script>', ...)). This filter is ASCII-case-sensitive and fails to identify variations such as </SCRIPT>, </script >, or </script/>, allowing an attacker to escape the script context and execute arbitrary JavaScript in the origin of the development server. This issue affects @quasar/render-ssr-error versions 2.2.3 and below, and @quasar/app-vite versions 3.2.0 and below.

Attack Chain

1. The attacker scans the network for development servers listening on Quasar's default ports or configured ports that are exposed via the 0.0.0.0 binding.
2. The attacker triggers a server-side rendering (SSR) or static site generation (SSG) error by sending a malformed request that causes the application logic to throw an exception.
3. The Quasar development server invokes renderSSRError, which collects the server's environment variables (including cloud credentials, tokens, and database strings) and request metadata.
4. The framework serializes this information into a 500 error response page.
5. The attacker retrieves the full environment dump via an unauthenticated GET request.
6. To achieve code execution, the attacker provides a malicious payload in an HTTP header or a cookie that, when processed by the disclosure page, breaks out of the script tag using an unescaped tag like </SCRIPT >.
7. The developer's browser renders the malicious script, allowing the attacker to execute code in the local dev environment context.

Impact

Successful exploitation allows for the unauthorized exfiltration of highly sensitive development credentials, including AWS secret keys, GitHub or NPM registry tokens, and database connection strings. By chaining the information disclosure with the HTML injection vulnerability, an attacker can also gain JavaScript execution within the developer's browser, potentially leading to session hijacking or local file interactions. This represents a significant risk for any organization utilizing Quasar in a networked development environment.

Recommendation

1. Upgrade affected projects to versions of @quasar/render-ssr-error and @quasar/app-vite that include the patch for CVE-2026-106106.
2. Ensure the development server is configured to bind to 127.0.0.1 rather than 0.0.0.0 to restrict access to the local machine.
3. Implement strict network segmentation for development environments to prevent unauthorized network access to local development ports.
4. Audit local development environments for potential credential leakage if the vulnerable version was previously exposed to any untrusted network segments.