CVE-2022-40482 in Laravel
Summary
by MITRE • 04/25/2023
The authentication method in Laravel 8.x through 9.x before 9.32.0 was discovered to be vulnerable to user enumeration via timeless timing attacks with HTTP/2 multiplexing. This is caused by the early return inside the hasValidCredentials method in the Illuminate\Auth\SessionGuard class when a user is found to not exist.
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Analysis
by VulDB Data Team • 02/03/2025
The vulnerability identified as CVE-2022-40482 represents a critical timing attack susceptibility within the Laravel framework authentication mechanism. This flaw exists in versions 8.x through 9.x prior to 9.32.0 and specifically targets the authentication flow through the Illuminate\Auth\SessionGuard class. The vulnerability stems from the implementation pattern where the authentication system returns early when a user is determined to not exist, creating measurable timing differences that can be exploited by attackers to determine the existence of specific user accounts. The issue becomes particularly pronounced when HTTP/2 multiplexing is employed, as this protocol characteristic amplifies the timing discrepancies that attackers can observe and measure. This timing-based user enumeration attack allows malicious actors to systematically identify valid user accounts within the system by analyzing response times from authentication requests.
The technical implementation flaw resides in the hasValidCredentials method within the SessionGuard class, where the system performs an early return when a user does not exist, but continues to perform password verification checks for existing users. This differential execution time creates a timing side channel that attackers can exploit through careful measurement of response durations. The vulnerability specifically affects the password verification process where the system's behavior changes based on whether a user account exists, enabling attackers to distinguish between valid and invalid user accounts through timing measurements. The timing variations are subtle but measurable, particularly when HTTP/2 multiplexing is in use, which can introduce additional network-level timing artifacts that compound the vulnerability. This pattern aligns with CWE-208, which describes timing side channels that can reveal information about system behavior through timing differences.
The operational impact of this vulnerability extends beyond simple user enumeration, as it creates a foundation for more sophisticated attacks including brute force attempts, credential stuffing, and account takeover operations. An attacker with access to the vulnerable system can systematically test multiple username and password combinations, using the timing variations to identify which usernames are valid, thereby reducing the search space for successful credential guessing. The vulnerability is particularly dangerous because it can be exploited without requiring elevated privileges or special access conditions, making it accessible to any attacker who can submit authentication requests to the target system. The impact is exacerbated by the fact that this vulnerability affects a widely used web application framework, meaning that countless applications and services may be vulnerable if they are not properly updated. This creates a significant risk for organizations that rely on Laravel applications for their web services and user authentication systems.
Mitigation strategies for CVE-2022-40482 require immediate action to update affected Laravel installations to version 9.32.0 or later, where the vulnerability has been addressed through implementation of constant-time comparison algorithms for password verification. Organizations should also implement rate limiting and account lockout mechanisms to prevent automated enumeration attacks from succeeding even if timing-based techniques are not fully mitigated. Network-level protections such as load balancer configurations that normalize response times and the implementation of authentication throttling can provide additional defense layers. Security teams should conduct comprehensive vulnerability assessments across all Laravel applications and ensure that proper monitoring is in place to detect unusual authentication patterns that may indicate enumeration attempts. The fix implemented in the patched versions addresses the core timing issue by ensuring that all authentication attempts take approximately equal time regardless of whether the user exists, thereby eliminating the timing side channel that enabled the attack. This aligns with the ATT&CK framework's credential access tactics, particularly those involving account enumeration and credential stuffing, where the vulnerability represents a critical weakness that enables these attack patterns to succeed.