CVE-2009-2687 in PHP
Summary
by MITRE • 01/25/2023
The exif_read_data function in the Exif module in PHP before 5.2.10 allows remote attackers to cause a denial of service (crash) via a malformed JPEG image with invalid offset fields, a different issue than CVE-2005-3353.
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Analysis
by VulDB Data Team • 02/13/2025
The vulnerability identified as CVE-2009-2687 represents a critical denial of service flaw within PHP's Exif module that affects versions prior to 5.2.10. This vulnerability specifically targets the exif_read_data function which is responsible for parsing Exif metadata from JPEG images. The flaw manifests when the function encounters malformed JPEG files containing invalid offset fields, causing the PHP interpreter to crash and terminate unexpectedly. This behavior constitutes a remote denial of service condition where an attacker can remotely trigger system instability by uploading or referencing specially crafted JPEG images that exploit this parsing vulnerability.
The technical mechanism behind this vulnerability involves the improper handling of malformed offset fields within JPEG image structures during the Exif metadata parsing process. When PHP's Exif module attempts to read and process these invalid offset values, it fails to properly validate the data structure before attempting to access memory locations or perform calculations based on these malformed offsets. This leads to memory access violations or buffer overflows that cause the PHP process to terminate abruptly. The vulnerability differs from CVE-2005-3353 in that it specifically targets offset field manipulation rather than other forms of Exif parsing issues, making it a distinct but related class of vulnerability within the same module. The flaw exists at the level of the Exif parsing library integration within PHP, where insufficient bounds checking and input validation allows malformed data to propagate through the parsing pipeline.
The operational impact of CVE-2009-2687 extends beyond simple service disruption to potentially compromise the availability of web applications that rely on PHP for image processing or metadata handling. In web environments where users can upload or reference JPEG images, an attacker can exploit this vulnerability to crash web server processes, leading to complete service unavailability for legitimate users. This is particularly dangerous in high-traffic environments where repeated exploitation can cause sustained denial of service conditions, potentially affecting multiple concurrent users or even entire web applications. The vulnerability affects both direct image processing scenarios and indirect usage patterns where Exif data is read during image validation or thumbnail generation processes, amplifying the potential attack surface.
Mitigation strategies for CVE-2009-2687 primarily focus on upgrading to PHP versions 5.2.10 or later where the vulnerability has been addressed through improved input validation and bounds checking mechanisms. System administrators should implement immediate patch management procedures to update all affected PHP installations and verify that the updated versions properly handle malformed JPEG files. Additional defensive measures include implementing strict image validation processes that sanitize or reject potentially malicious JPEG files before they reach the Exif parsing stage, deploying web application firewalls that can detect and block suspicious image file patterns, and implementing process monitoring to detect and restart crashed PHP processes automatically. From a cybersecurity perspective, this vulnerability aligns with CWE-125 (Out-of-bounds Read) and CWE-787 (Out-of-bounds Write) classifications, representing memory safety issues that can lead to system instability. The ATT&CK framework categorizes this vulnerability under T1499.004 (Endpoint Denial of Service) and T1595.001 (Network Denial of Service) techniques, emphasizing its potential for both local and remote exploitation scenarios that can compromise system availability and service integrity.