CVE-2025-14177 in PHP
Summary
by MITRE • 12/27/2025
In PHP versions:8.1.* before 8.1.34, 8.2.* before 8.2.30, 8.3.* before 8.3.29, 8.4.* before 8.4.16, 8.5.* before 8.5.1, the getimagesize() function may leak uninitialized heap memory into the APPn segments (e.g., APP1) when reading images in multi-chunk mode (such as via php://filter). This occurs due to a bug in php_read_stream_all_chunks() that overwrites the buffer without advancing the pointer, leaving tail bytes uninitialized. This may lead to information disclosure of sensitive heap data and affect the confidentiality of the target server.
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Analysis
by VulDB Data Team • 02/02/2026
The vulnerability identified as CVE-2025-14177 represents a critical information disclosure flaw in PHP's image processing capabilities that affects multiple version streams including 8.1., 8.2., 8.3., 8.4., and 8.5.*. This vulnerability specifically targets the getimagesize() function which is commonly used to determine image dimensions and metadata, making it a frequent target in web applications that process user-uploaded images. The flaw manifests when PHP reads images in multi-chunk mode, particularly through php://filter streams, creating a scenario where uninitialized memory segments can be inadvertently exposed.
The technical root cause resides in the php_read_stream_all_chunks() function which fails to properly advance memory pointers during buffer operations. This memory management error creates a condition where the buffer overwrite operation does not increment the pointer position, resulting in trailing bytes remaining uninitialized within the memory allocation. These uninitialized heap segments contain residual data from previous operations, potentially including sensitive information such as cryptographic keys, session tokens, or application secrets that were previously stored in the same memory regions. The vulnerability is particularly concerning because it operates at the heap level where PHP applications store various types of sensitive data.
The operational impact of this vulnerability extends beyond simple information disclosure as it can compromise the confidentiality of server environments and potentially enable more sophisticated attacks. When attackers can leverage this vulnerability through crafted image files or manipulated php://filter streams, they gain access to uninitialized heap memory that may contain sensitive application data. This information leakage could expose session identifiers, database connection details, or other critical system information that would otherwise remain protected. The vulnerability affects any PHP application that processes user-supplied images through the getimagesize() function, particularly web applications that handle file uploads or image processing operations, making it a widespread concern across the PHP ecosystem.
The vulnerability aligns with CWE-248, an information exposure weakness that specifically addresses the disclosure of uninitialized memory, and can be mapped to ATT&CK technique T1566.001 for initial access through malicious file uploads. Organizations should prioritize immediate patching of affected PHP versions to address this vulnerability, with the specific remediation targets being PHP 8.1.34, 8.2.30, 8.3.29, 8.4.16, and 8.5.1 respectively. Additionally, implementing proper input validation and sanitization measures, restricting php://filter usage, and monitoring for unusual getimagesize() function calls can serve as effective mitigations. Security teams should also consider implementing memory access controls and regular security scanning to detect potential exploitation attempts. The vulnerability demonstrates the importance of proper memory management in language runtimes and highlights how seemingly benign image processing functions can become attack vectors when memory handling is flawed.