CVE-2026-16768 in gdk-pixbuf
Summary
by MITRE • 07/23/2026
A flaw was found in gdk-pixbuf. When parsing a specially crafted ICO file with pixel values that exceed the defined palette range, an out-of-bounds read can occur due to improper bounds checking against the actual palette size. This vulnerability causes heap bytes to be interpreted as valid palette indices and rendered as RGB pixel values in the output image, allowing an attacker to extract heap content via the generated output, such as a thumbnail.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 07/23/2026
This vulnerability exists within the gdk-pixbuf library which is widely used for image processing in graphical applications across linux desktop environments. The flaw manifests when the library processes specially crafted ICO files that contain pixel values exceeding the defined palette range. The root cause lies in inadequate bounds checking mechanisms that fail to validate palette indices against the actual palette size during ICO file parsing operations. This improper validation creates a condition where memory addresses within the heap can be interpreted as valid palette indices, leading to out-of-bounds read conditions.
The technical implementation of this vulnerability involves the manipulation of ICO file structures to include invalid pixel data that exceeds the expected palette boundaries. When the gdk-pixbuf parser encounters these malformed values, it does not properly constrain the index values against the actual palette dimensions, resulting in memory access patterns that traverse beyond allocated heap regions. The heap content is subsequently interpreted as valid palette indices and translated into RGB pixel values within the output image, effectively creating a data leakage mechanism.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks through heap content exposure. When thumbnails or other rendered images are generated from these malicious ICO files, the extracted heap data can contain sensitive information such as cryptographic keys, application state data, or other confidential memory contents. This makes the vulnerability particularly dangerous in environments where image processing occurs with untrusted input sources, as it allows attackers to harvest potentially valuable data from memory regions that should remain protected.
This vulnerability aligns with CWE-129 which addresses insufficient bounds checking and CWE-200 which covers information exposure. From an attack perspective, it maps to techniques described in the ATT&CK framework under T1566 for phishing with social engineering and T1005 for data from local system. The heap content extraction capability places this vulnerability in the category of information disclosure attacks that can be leveraged for further exploitation. Mitigation strategies should focus on implementing robust bounds checking mechanisms, validating all palette indices against actual palette dimensions, and applying input sanitization measures to prevent malformed ICO files from being processed. Updates to the gdk-pixbuf library should include comprehensive memory validation routines that ensure all index values remain within acceptable ranges during image parsing operations.
The broader implications of this vulnerability highlight the importance of proper memory management in image processing libraries, particularly those handling multiple file formats with varying structural requirements. Given the widespread use of gdk-pixbuf in desktop environments and application frameworks, this flaw represents a significant security risk that could be exploited across numerous applications and systems. System administrators should prioritize patching affected installations and consider implementing input validation measures at network boundaries to prevent exploitation attempts. The vulnerability demonstrates how seemingly minor implementation flaws in core libraries can create substantial security risks when dealing with untrusted data inputs in graphical processing contexts.
This issue particularly affects desktop environments using GTK-based applications, where thumbnail generation and image rendering frequently process user-provided content without adequate sanitization. The vulnerability's exploitation potential increases when considering that many applications automatically generate thumbnails for files, making the attack surface larger than initially apparent. The heap data extraction capability also means that attackers could potentially gather information about memory layout, application state, or other sensitive data structures present in the heap at the time of processing, providing valuable intelligence for more advanced exploitation techniques.