CVE-2025-43931 in flask-boilerplate
Summary
by MITRE • 07/07/2025
flask-boilerplate through a170e7c allows account takeover via the password reset feature because SERVER_NAME is not configured and thus a reset depends on the Host HTTP header.
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Analysis
by VulDB Data Team • 07/07/2025
The vulnerability identified as CVE-2025-43931 affects flask-boilerplate versions up to and including commit a170e7c and represents a critical account takeover risk stemming from improper configuration of the SERVER_NAME parameter. This flaw specifically impacts the password reset functionality of web applications built on this framework, creating a pathway for malicious actors to compromise user accounts. The vulnerability operates by exploiting the application's reliance on the HTTP Host header for generating password reset URLs, which creates an attack surface when the SERVER_NAME configuration is absent or improperly set.
The technical root cause of this vulnerability lies in the application's failure to properly validate and sanitize the Host header during password reset operations. When SERVER_NAME is not explicitly configured, the application defaults to using the Host header value directly in the reset URL generation process. This creates a scenario where an attacker can manipulate the Host header to inject malicious domain values into the reset tokens, potentially redirecting users to attacker-controlled domains. The flaw directly corresponds to CWE-601 URL Redirection to Untrusted Site vulnerability, which occurs when applications redirect users to external domains without proper validation. This weakness allows for sophisticated attacks including phishing campaigns and credential harvesting, as users may be misled into believing they are interacting with legitimate password reset pages.
The operational impact of this vulnerability extends beyond simple account compromise, as it enables a range of sophisticated attack vectors within the broader adversary tactics and techniques framework. Attackers can leverage this vulnerability to perform session hijacking, credential stuffing attacks, and social engineering campaigns that exploit user trust in the application's password reset functionality. The vulnerability's exploitation requires minimal technical skill and can be automated, making it particularly dangerous in environments with numerous user accounts. According to ATT&CK framework, this vulnerability maps to T1566 (Phishing) and T1110 (Brute Force) tactics, as attackers can combine this weakness with other techniques to maximize their attack surface. The impact is particularly severe in multi-tenant environments or applications with high user volume, where a single compromised account can provide access to larger datasets or system resources.
Mitigation strategies for this vulnerability must address both immediate configuration fixes and long-term architectural improvements. The primary remediation involves explicitly setting the SERVER_NAME configuration parameter to a trusted value, ensuring that all generated reset URLs use the correct domain rather than relying on potentially manipulated Host headers. Organizations should implement strict header validation mechanisms that verify the Host header against known good values or implement proper URL sanitization routines. Additional protective measures include implementing rate limiting on password reset requests, adding multi-factor authentication for sensitive operations, and conducting regular security audits of application configuration settings. The vulnerability serves as a reminder of the critical importance of proper input validation and configuration management in web applications, particularly those handling user authentication and authorization processes. Security teams should prioritize patching affected systems and implementing comprehensive monitoring for suspicious password reset activities that may indicate exploitation attempts.