CVE-2026-64635 in Service Provider Console
Summary
by MITRE • 07/30/2026
Improper handling of the returnUrl parameter in the Forgot Password function of Veeam Service Provider Console allows an unauthenticated attacker to control the domain of the generated password reset link. When the targeted user clicks the link delivered by email, the reset code is transmitted to an attacker-controlled host, allowing the attacker to take over the account.
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Analysis
by VulDB Data Team • 07/30/2026
This vulnerability represents a critical authentication bypass flaw in Veeam Service Provider Console's password recovery mechanism that fundamentally undermines the security of user accounts. The issue stems from improper input validation and sanitization of the returnUrl parameter within the Forgot Password functionality, creating an open redirect vulnerability that enables attackers to manipulate the destination of password reset links. This weakness directly maps to CWE-601 Open Redirect vulnerability classification, where the application fails to validate that the redirect target domain is trusted or controlled by the legitimate service provider. The vulnerability exists at the application logic level where user-supplied input is not properly sanitized before being used to construct the password reset URL, allowing arbitrary domains to be specified in the redirect parameter.
The operational impact of this vulnerability is severe and directly enables account takeover attacks without requiring any authentication credentials from the victim. An attacker can craft a malicious password reset link with a controlled returnUrl parameter pointing to their own server, then send this link via phishing or social engineering techniques to targeted users. When victims click these links, they are redirected to the attacker-controlled domain where the password reset codes are transmitted, providing the attacker with the ability to reset passwords and gain full access to compromised accounts. This attack vector aligns with ATT&CK technique T1566.001 Phishing: Spearphishing Attachment and follows the broader credential theft attack patterns described in the MITRE framework.
The technical exploitation requires minimal sophistication as attackers only need to modify the returnUrl parameter in the password reset URL, typically by appending or modifying a query string parameter that gets directly incorporated into the final redirect destination. This vulnerability affects the authentication flow at multiple levels including client-side navigation behavior and server-side URL construction logic. The lack of domain validation creates an attack surface where any user with access to the password recovery endpoint can be targeted, making it particularly dangerous in environments with many users or when attackers can mass produce such links. This issue demonstrates a fundamental failure in implementing proper input validation and output encoding as recommended by OWASP Top 10 and other security standards.
Mitigation strategies should focus on implementing strict domain validation for all redirect parameters, ensuring that only pre-approved domains or subdomains are permitted in the returnUrl parameter. The application should maintain an explicit whitelist of trusted domains and reject any redirection attempts to external or untrusted locations. Additionally, implementing proper URL encoding, input sanitization, and output validation techniques can prevent malicious manipulation of redirect parameters. Security measures should include logging all redirect attempts for monitoring unusual patterns and implementing rate limiting on password reset requests to prevent abuse. Organizations should also consider implementing multi-factor authentication as a defense-in-depth measure, while regular security assessments and penetration testing should verify that such vulnerabilities are properly addressed through proper application security controls and secure coding practices.