CVE-2018-19790 in Symfony
Summary
by MITRE
An open redirect was discovered in Symfony 2.7.x before 2.7.50, 2.8.x before 2.8.49, 3.x before 3.4.20, 4.0.x before 4.0.15, 4.1.x before 4.1.9 and 4.2.x before 4.2.1. By using backslashes in the `_failure_path` input field of login forms, an attacker can work around the redirection target restrictions and effectively redirect the user to any domain after login.
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Analysis
by VulDB Data Team • 06/19/2023
The vulnerability identified as CVE-2018-19790 represents a critical open redirect flaw within the Symfony web application framework that affects multiple version lines including 2.7.x through 2.8.49, 3.x through 3.4.20, and various 4.x releases. This security issue stems from insufficient validation of redirection targets in the authentication flow, specifically within the `_failure_path` input field processing mechanism. The vulnerability allows attackers to manipulate the redirection behavior during failed login attempts, potentially leading to phishing attacks or malicious domain redirection.
The technical exploitation of this vulnerability relies on the improper handling of backslash characters within the `_failure_path` parameter which is used to specify where users should be redirected upon failed authentication attempts. When an attacker crafts a malicious input containing backslashes in the login form's failure path field, the framework's validation logic fails to properly sanitize or restrict the target domain. This weakness falls under CWE-601, which specifically addresses open redirect vulnerabilities where applications redirect users to untrusted domains without proper validation. The flaw demonstrates a classic case of inadequate input sanitization and validation in web application security controls.
The operational impact of this vulnerability extends beyond simple redirection attacks and creates significant risks for organizations using affected Symfony versions. Attackers can leverage this weakness to redirect users to malicious domains, potentially facilitating credential theft through phishing campaigns or delivering malware through compromised redirection paths. The vulnerability affects the core authentication mechanism of Symfony applications, making it particularly dangerous as it can be exploited during the login process when users are already in a vulnerable state. This type of attack aligns with ATT&CK technique T1566.001, which covers phishing campaigns targeting credential access through malicious redirects.
Organizations utilizing affected Symfony versions should immediately implement mitigations including upgrading to patched releases such as Symfony 2.7.50, 2.8.49, 3.4.20, 4.0.15, 4.1.9, and 4.2.1 or later. Additionally, administrators should review and implement proper input validation for all authentication-related parameters, particularly focusing on sanitizing special characters including backslashes in redirection paths. The fix typically involves strengthening the validation logic to properly handle and reject malicious redirection targets while maintaining legitimate functionality for authorized redirects. Security teams should also consider implementing additional monitoring for suspicious redirect patterns and establishing proper access controls to limit the impact of potential exploitation attempts.