CVE-2016-4070 in PHP
Prediction
by VulDB Data Team • 07/06/2025
A vulnerability has been found in PHP up to 5.5.33/5.6.19/7.0.4. This affects the function php_raw_url_encode of the file ext/standard/url.c of the component rawurlencode Handler. The manipulation leads to denial of service. The attack can be initiated remotely. The real existence of this vulnerability is still doubted at the moment. Upgrading to version 5.5.34, 5.6.20 and 7.0.5 is able to mitigate this issue. It is recommended to upgrade the affected component.
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Analysis
by VulDB Data Team • 07/06/2025
The vulnerability identified as CVE-2016-4070 represents an integer overflow condition within PHP's rawurlencoding functionality that could potentially lead to application instability. This issue affects multiple PHP versions including those before 5.5.34, 5.6.x before 5.6.20, and 7.x before 7.0.5, demonstrating the widespread nature of the flaw within the PHP ecosystem. The vulnerability specifically resides in the php_raw_url_encode function located within the ext/standard/url.c source file, indicating a core component of PHP's URL handling capabilities is compromised.
The technical exploitation of this vulnerability occurs when a remote attacker submits an exceptionally long string to the rawurlencode function, which triggers the integer overflow condition during the encoding process. This overflow results in the application crashing and becoming unavailable to legitimate users, constituting a denial of service attack vector. The integer overflow manifests when the function attempts to process input data that exceeds the maximum value that can be represented by the integer data type being used, causing unexpected behavior in the program execution flow. This type of vulnerability falls under the CWE-190 category of integer overflow, which is classified as a common weakness in software development practices.
From an operational perspective, this vulnerability presents significant risks to web applications that rely on PHP for URL encoding operations, particularly those handling user input or processing external data sources. The denial of service impact can disrupt service availability and potentially affect business operations, especially in high-traffic environments where application stability is critical. Attackers could exploit this weakness to repeatedly crash applications, leading to sustained service disruption and potential financial losses. The vulnerability's classification as a denial of service issue aligns with ATT&CK technique T1499.004 for network denial of service, though the vendor's stance on whether this constitutes a security issue remains disputed.
Organizations should implement immediate mitigations including upgrading to patched PHP versions, which address the integer overflow condition in the rawurlencoding function. Additionally, input validation mechanisms should be strengthened to limit the length of strings processed by the rawurlencode function, providing an additional layer of defense against potential exploitation. Regular security assessments and monitoring of PHP applications for similar integer overflow vulnerabilities should be conducted to maintain overall system security posture. The vendor's position on this issue's security classification should be carefully considered when determining risk tolerance levels and appropriate response measures.