CVE-2013-6629 in Java SE
Summary
by MITRE
The get_sos function in jdmarker.c in (1) libjpeg 6b and (2) libjpeg-turbo through 1.3.0, as used in Google Chrome before 31.0.1650.48, Ghostscript, and other products, does not check for certain duplications of component data during the reading of segments that follow Start Of Scan (SOS) JPEG markers, which allows remote attackers to obtain sensitive information from uninitialized memory locations via a crafted JPEG image.
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Analysis
by VulDB Data Team • 11/25/2025
The vulnerability identified as CVE-2013-6629 represents a critical information disclosure flaw within the libjpeg library ecosystem, affecting versions through 1.3.0 including the widely used libjpeg 6b. This vulnerability specifically targets the get_sos function in the jdmarker.c component, which is responsible for processing JPEG marker segments during image decoding operations. The flaw manifests when the function fails to properly validate and check for duplicate component data within segments that follow the Start Of Scan (SOS) JPEG markers, creating a condition where uninitialized memory contents can be inadvertently exposed to attackers.
The technical implementation of this vulnerability stems from inadequate input validation within the JPEG decoding process. During normal JPEG processing, the SOS marker indicates the beginning of the compressed data segment that contains the actual image data. The get_sos function should rigorously validate the component specifications and ensure that data duplication does not occur, but due to the missing validation checks, the function allows for malformed JPEG data to be processed without proper boundary enforcement. This allows attackers to craft malicious JPEG images that exploit the lack of duplicate checking, causing the decoder to read from uninitialized memory regions and potentially expose sensitive data such as cryptographic keys, passwords, or other confidential information that may have previously resided in those memory locations.
The operational impact of this vulnerability extends across multiple software platforms that rely on libjpeg for image processing capabilities. Notable affected applications include Google Chrome versions prior to 31.0.1650.48, where the vulnerability could be exploited through web-based attacks, as well as Ghostscript and numerous other products that utilize libjpeg for image handling. Attackers can leverage this vulnerability by preparing specially crafted JPEG files that trigger the flawed memory access patterns, potentially leading to information disclosure attacks that compromise the confidentiality of data stored in memory. The vulnerability is particularly concerning because it operates at the decoding level, meaning that even images that appear benign to users could contain hidden malicious data structures designed to exploit this specific flaw.
This vulnerability maps directly to CWE-125: Uninitialized Memory Read and CWE-704: Incorrect Type Conversion or Cast, with implications that align with ATT&CK technique T1059.007: Command and Scripting Interpreter: PowerShell and T1566.001: Phishing: Spearphishing Attachment. The attack vector typically involves social engineering campaigns where users are tricked into opening malicious JPEG files, with the information disclosure occurring during the normal image rendering process. Mitigation strategies include updating to patched versions of libjpeg and libjpeg-turbo, implementing strict input validation for JPEG file processing, and deploying network-based intrusion detection systems that can identify suspicious JPEG file patterns. Organizations should also consider implementing application sandboxing for image processing functions and monitoring for unusual memory access patterns that might indicate exploitation attempts. The vulnerability underscores the importance of proper input validation in cryptographic and image processing libraries, as these components often handle untrusted data from external sources and must maintain strict security boundaries to prevent information leakage.