CVE-2026-104066 in Scribus
Summary
by MITRE • 10/30/2026
Scribus before 1.6.7 contains a heap buffer overflow vulnerability in the Mac PICT image loader and import plugin when unpacking 4-bit indexed pixel data. Attackers can supply a crafted PICT file with inconsistent width and row data that, when placed or imported, writes out of bounds, causing crashes or code execution.
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Analysis
by VulDB Data Team • 10/30/2026
The vulnerability identified in Scribus versions prior to 1.6.7 represents a critical heap-based buffer overflow within the Macintosh Picture (PICT) image loader component. This specific flaw arises during the processing and unpacking of 4-bit indexed pixel data, which is a legacy graphics format often encountered when importing historical or specialized design assets. The core technical deficiency lies in the application's failure to adequately validate input dimensions against allocated memory buffers. Specifically, when a crafted PICT file containing inconsistent width parameters relative to its row data is processed, the parser miscalculates the required buffer size or fails to enforce strict bounds checking during the pixel unpacking routine. This logical error allows an attacker to write data beyond the boundaries of the heap-allocated memory region designated for image processing.
From a technical perspective, this vulnerability aligns with CWE-120, which classifies buffer copies without checks on length as a classic cause of memory corruption issues. The exploitation vector relies on the precise manipulation of file metadata and pixel array structures to trigger an out-of-bounds write operation. By supplying a maliciously constructed PICT file where the declared width does not match the actual row data size, an attacker can force the application to overwrite adjacent heap memory segments. This overwriting capability is particularly dangerous as it allows for arbitrary code execution if the overwritten memory contains function pointers or control flow metadata that the program subsequently utilizes. The vulnerability effectively bypasses standard safety mechanisms by exploiting the trust placed in file format parsers to correctly interpret binary data structures without rigorous validation of internal consistency between header fields and payload content.
The operational impact of this flaw is severe, encompassing both stability risks and high-severity security breaches. In its least impactful form, triggering this vulnerability results in application crashes due to memory access violations, leading to a denial-of-service condition for users attempting to open or import compromised files. However, the primary concern lies in the potential for remote code execution. An attacker who can trick a user into opening a specially crafted PICT file within Scribus could execute arbitrary commands on the victim's system with the privileges of the application process. This capability enables further compromise steps such as data exfiltration, installation of persistent malware, or pivoting to other systems within a network if the compromised host is part of a larger infrastructure. The risk is exacerbated by the fact that Scribus is often used in professional design environments where users may frequently import assets from untrusted sources or collaborate with external partners who might inadvertently provide malicious files.
Mitigation strategies must prioritize immediate software updates and defensive operational practices. Users running versions of Scribus earlier than 1.6.7 should upgrade to the latest stable release immediately, as this version contains patches that enforce stricter validation on image dimensions and buffer allocations during PICT processing. In environments where upgrading is not instantly feasible, organizations should implement strict file filtering policies at network perimeters or email gateways to block or quarantine suspicious graphic files before they reach end-user workstations. Additionally, enabling application sandboxing can limit the blast radius of any potential exploitation by restricting the compromised process's access to critical system resources and sensitive data stores. Security awareness training for design teams is also recommended to emphasize caution when opening image files from unknown origins, reinforcing that even standard file formats like PICT can serve as vectors for sophisticated attacks exploiting memory corruption vulnerabilities.
This incident underscores the importance of robust input validation in multimedia processing libraries, a principle central to secure software development lifecycle standards such as OWASP Software Verification and Validation guidelines. The vulnerability also maps to MITRE ATT&CK techniques related to initial access via malicious files and execution through exploited applications. By addressing these memory safety issues at the source code level and maintaining vigilant update cycles, organizations can significantly reduce their attack surface against similar heap-based exploitation attempts targeting desktop publishing and graphic design software ecosystems.