CVE-2019-10912 in Symfony
Summary
by MITRE
In Symfony before 2.8.50, 3.x before 3.4.26, 4.x before 4.1.12, and 4.2.x before 4.2.7, it is possible to cache objects that may contain bad user input. On serialization or unserialization, this could result in the deletion of files that the current user has access to. This is related to symfony/cache and symfony/phpunit-bridge.
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Analysis
by VulDB Data Team • 09/21/2023
This vulnerability affects Symfony framework versions prior to specific patches, creating a critical security risk through improper object caching mechanisms. The issue stems from the cache component's handling of serialized objects that may contain malicious user input, allowing for arbitrary file deletion when these objects are subsequently unserialized. The vulnerability impacts multiple Symfony versions including 2.8.50, 3.4.26, 4.1.12, and 4.2.7, indicating a widespread problem across the framework's architecture. This flaw represents a classic deserialization vulnerability that can be exploited by attackers to manipulate the application's file system operations.
The technical implementation of this vulnerability involves the symfony/cache component's serialization process where user-supplied data becomes embedded within cached objects. When these objects are later unserialized, the malicious input can trigger unintended file system operations, specifically enabling file deletion. This occurs because the caching mechanism does not properly sanitize or validate user input before storing it in serialized form, creating a path for privilege escalation attacks. The vulnerability is particularly dangerous because it leverages the legitimate caching functionality to execute malicious operations, making detection more challenging.
The operational impact of CVE-2019-10912 extends beyond simple file deletion, potentially allowing attackers to compromise entire application environments. Attackers can exploit this vulnerability to remove critical application files, configuration data, or even system files accessible to the web server process. The risk is amplified when applications use Symfony's cache components for storing user-generated content or when the application runs with elevated privileges. This vulnerability directly relates to CWE-502, which describes deserialization of untrusted data, and aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as the exploitation may involve executing commands through file system manipulation. The attack surface is broad since many Symfony applications utilize caching for performance optimization, making this vulnerability prevalent across various deployment scenarios.
Mitigation strategies should focus on immediate version upgrades to patched Symfony releases, specifically updating to 2.8.50, 3.4.26, 4.1.12, or 4.2.7 respectively. Organizations should also implement strict input validation and sanitization before any user data is cached, ensuring that serialized objects contain only trusted content. Additional protective measures include restricting file system permissions for web server processes, implementing proper access controls, and monitoring cache operations for unusual patterns. Security teams should conduct comprehensive code reviews to identify any custom caching implementations that may be vulnerable, while also considering the deployment of web application firewalls to detect and block exploitation attempts. The vulnerability demonstrates the critical importance of proper sanitization in serialization processes and highlights the need for security testing of caching mechanisms within application frameworks.