CVE-2023-39655 in couch-auth
Summary
by MITRE • 01/03/2024
A host header injection vulnerability exists in the NPM package @perfood/couch-auth versions <= 0.20.0. By sending a specially crafted host header in the forgot password request, it is possible to send password reset links to users which, once clicked, lead to an attacker-controlled server and thus leak the password reset token. This may allow an attacker to reset other users' passwords and take over their accounts.
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Analysis
by VulDB Data Team • 06/18/2025
The vulnerability identified as CVE-2023-39655 represents a critical host header injection flaw within the @perfood/couch-auth npm package affecting versions up to 0.20.0. This security weakness stems from improper validation of host headers in the password reset functionality, creating a pathway for attackers to manipulate the domain information used in email notifications. The flaw specifically manifests during forgot password requests where the application fails to properly sanitize or validate the host header value before constructing password reset URLs. This vulnerability directly maps to CWE-614, which categorizes insecure direct object references and improper input validation in web applications. The attack vector exploits the trust relationship between the application and the host header, allowing malicious actors to redirect users to attacker-controlled domains when they click on password reset links.
The technical implementation of this vulnerability occurs because the password reset email generation process incorporates the host header value directly into the constructed URL without proper sanitization or validation. When users request password resets, the application generates links containing reset tokens that are delivered to their email addresses. However, due to the host header injection, these links can be manipulated to point to attacker-controlled servers instead of the legitimate application domain. This manipulation enables attackers to capture the password reset tokens as they are accessed by users, effectively providing them with the means to reset any user's password and assume full account control. The vulnerability demonstrates a classic example of insecure header handling that violates fundamental security principles of input validation and output encoding. The flaw operates at the application layer and can be exploited through HTTP requests, making it particularly dangerous as it requires minimal privileges to execute.
The operational impact of CVE-2023-39655 extends beyond simple account takeover to encompass broader security implications for affected systems. Attackers can leverage this vulnerability to systematically compromise multiple user accounts, potentially leading to data breaches, unauthorized access to sensitive information, and complete system compromise. The vulnerability affects the authentication and authorization mechanisms of applications using the vulnerable npm package, undermining the security posture of organizations that rely on proper password reset functionality. From an attacker's perspective, this vulnerability provides a direct path to account takeover with minimal detection risk, as the manipulation occurs at the network layer during legitimate password reset workflows. The attack can be automated and scaled across multiple user accounts, making it particularly dangerous for applications with large user bases. The vulnerability also enables credential stuffing attacks against other services where users may have reused passwords, amplifying the overall security impact. Organizations using affected versions of @perfood/couch-auth face significant risk of unauthorized access and potential data exfiltration.
Mitigation strategies for CVE-2023-39655 require immediate action to address the root cause through proper input validation and header sanitization. The most effective immediate fix involves updating to a patched version of the @perfood/couch-auth package, ensuring that host headers are properly validated and sanitized before being used in URL construction. Organizations should implement strict validation of host headers against a predefined whitelist of trusted domains, preventing injection of malicious host values into password reset emails. The solution should incorporate proper input sanitization techniques that strip or encode potentially dangerous characters from host header values. Security teams must also consider implementing additional layers of protection such as rate limiting on password reset requests and monitoring for unusual patterns in reset link access. From a defensive perspective, the vulnerability highlights the importance of secure coding practices and proper validation of user-supplied input in web applications. Organizations should conduct comprehensive security reviews of their npm dependencies and implement dependency management policies that automatically alert on vulnerable package versions. The remediation process should include thorough testing of the patched functionality to ensure that legitimate password reset workflows continue to operate correctly while eliminating the injection vector. Additionally, implementing web application firewalls and security monitoring can help detect and prevent exploitation attempts of similar vulnerabilities in the future.