CVE-2026-106106 in Quasar
Summary
by MITRE • 10/06/2026
Quasar Framework is a framework for building high-performance Vue.js user interfaces. Prior to @quasar/render-ssr-error 2.2.4 and @quasar/app-vite 3.3.0, renderSSRError() in utils/render-ssr-error/src/index.js used diagnostic data from utils/render-ssr-error/src/env.js to serialize process.env, request headers, and cookies into the HTTP page returned by serve.devError(), while the development server listened on all interfaces by default. Any network-adjacent client that reaches an SSR or SSG render failure through this development-only error path can obtain shell environment secrets. The renderer escaped only one exact lowercase script closing-tag spelling, so case variants and valid closing-tag delimiter variants in reflected diagnostic data could terminate the script element and inject markup; executing the injected code in a developer browser additionally requires the payload to accompany that developer's request. This issue is fixed in @quasar/render-ssr-error 2.2.4 and @quasar/app-vite 3.3.0.
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Analysis
by VulDB Data Team • 10/06/2026
The Quasar Framework, widely utilized for constructing high-performance Vue.js user interfaces, contained a critical security flaw within its server-side rendering error handling mechanism prior to the release of specific patch versions. The vulnerability resides in the renderSSRError function located in utils/render-ssr-error/src/index.js, which interacts with environment configuration data from utils/render-ssr-error/src/env.js during development mode. When an SSR or Static Site Generation process encounters a failure while running on the development server, this error path is triggered to display diagnostic information to the developer. However, the implementation failed to adequately sanitize sensitive system variables before inclusion in the HTTP response. Specifically, the function serialized and exposed critical environment secrets such as values from process.env, along with request headers and cookies, directly into the HTML page returned by serve.devError(). This behavior creates a significant Information Disclosure vulnerability, allowing any network-adjacent client that can trigger an SSR or SSG render failure to extract confidential configuration data and session tokens.
The severity of this information leak is compounded by the default networking configuration of the Quasar development server. By listening on all interfaces rather than restricting access to localhost only, the service becomes accessible from external networks within the same environment. This architectural choice means that an attacker does not need local shell access or direct browser interaction with the specific vulnerable page; they can simply send a crafted request designed to induce a render error and receive the sensitive diagnostic payload in return. The exposure of process.env variables often includes database credentials, API keys, JWT secrets, and other authentication tokens essential for application security. Furthermore, the inclusion of cookies and headers may reveal session identifiers or internal routing details that facilitate further reconnaissance or unauthorized access attempts against the development environment infrastructure.
Beyond simple information disclosure, the vulnerability also presents a risk of Cross-Site Scripting due to insufficient input sanitization within the error rendering logic. The renderer was designed to escape only one exact lowercase script closing tag spelling, leaving it vulnerable to case variations and other valid HTML delimiter variants that could terminate the current script element prematurely. If an attacker can control any part of the reflected diagnostic data, they may inject arbitrary markup or JavaScript code into the response page. While this injection requires the payload to accompany a developer's request, making it less suitable for automated remote exploitation without user interaction, it poses a threat in collaborative development environments where shared credentials or sensitive context might be present in browser sessions. This aspect aligns with CWE-79 Improper Neutralization of Input During Web Page Generation and represents a potential vector for session hijacking if the injected script executes within the developer's authenticated context.
The operational impact extends beyond immediate data theft to include broader security posture degradation during the development lifecycle. Developers relying on these tools may inadvertently commit sensitive environment variables to version control or share them with team members who do not require access, simply because they are exposed in error logs and network responses. The lack of strict separation between diagnostic output intended for local debugging and public-facing HTTP content violates fundamental security principles regarding least privilege and minimal exposure. This flaw is categorized under CWE-209 Generation of Error Message Containing Sensitive Information and maps to the ATT&CK technique T1537, which involves communicating through a protocol or service that allows data exfiltration without detection by standard monitoring tools often focused on production traffic patterns rather than development server anomalies.
To mitigate this vulnerability, organizations must immediately upgrade quasar/render-ssr-error to version 2.2.4 and quasar/app-vite to version 3.3.0 or later, as these releases contain the necessary patches for input sanitization and secure handling of diagnostic data. In addition to upgrading dependencies, development environments should be configured to bind exclusively to localhost interfaces, preventing external network access entirely during active development sessions. This practice ensures that even if a vulnerability exists in local tooling, it cannot be exploited by remote actors on the same network segment. Furthermore, developers should implement strict environment variable management practices, ensuring that sensitive credentials are not included in client-side accessible contexts and utilizing dedicated secret management solutions rather than plain text process.env variables for critical authentication data. Regular security audits of development toolchains are recommended to identify similar oversights in error handling routines across the entire stack.