CVE-2018-15133 in Laravel
Summary
by MITRE
In Laravel Framework through 5.5.40 and 5.6.x through 5.6.29, remote code execution might occur as a result of an unserialize call on a potentially untrusted X-XSRF-TOKEN value. This involves the decrypt method in Illuminate/Encryption/Encrypter.php and PendingBroadcast in gadgetchains/Laravel/RCE/3/chain.php in phpggc. The attacker must know the application key, which normally would never occur, but could happen if the attacker previously had privileged access or successfully accomplished a previous attack.
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Analysis
by VulDB Data Team • 02/03/2025
The vulnerability identified as CVE-2018-15133 represents a critical remote code execution flaw within the Laravel web application framework affecting versions through 5.5.40 and 5.6.x through 5.6.29. This vulnerability stems from an insecure deserialization pattern that occurs when the framework processes the X-XSRF-TOKEN header value during request handling. The flaw specifically manifests in the decrypt method located within Illuminate/Encryption/Encrypter.php, where user-controllable input undergoes deserialization without proper validation, creating an avenue for malicious code injection.
The technical exploitation of this vulnerability requires an attacker to possess the application's encryption key, which serves as a critical prerequisite for successful attack execution. This requirement significantly limits the attack surface but does not eliminate the threat entirely, as the application key could be compromised through prior successful attacks, credential theft, or misconfigurations that expose sensitive information. The vulnerability leverages the phpggc gadget chain framework, specifically targeting the PendingBroadcast class in the Laravel RCE gadget chain, which demonstrates how the deserialization process can be manipulated to execute arbitrary code on the target system.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with full control over the affected Laravel application server. This includes the ability to read, modify, or delete sensitive data, escalate privileges, and potentially use the compromised server as a pivot point for further attacks within the network infrastructure. The vulnerability's classification aligns with CWE-502, which addresses deserialization of untrusted data, and maps to ATT&CK technique T1059.007 for command and scripting interpreter, specifically through the use of PHP as the execution environment.
Organizations utilizing Laravel frameworks must implement immediate mitigations to address this vulnerability, including upgrading to patched versions of the framework where available. Additionally, security measures should focus on protecting application keys through proper key management practices, including regular rotation and secure storage mechanisms. Network segmentation and monitoring of suspicious X-XSRF-TOKEN header values can provide additional defense-in-depth layers. The vulnerability also underscores the importance of following secure coding practices, particularly regarding input validation and the avoidance of dangerous deserialization patterns in web applications, as outlined in OWASP Top 10 2017 category A08: Insecure Deserialization and the corresponding mitigation strategies found in NIST SP 800-53 security controls.