CVE-2026-120433 in Netpbm
Summary
by MITRE • 11/02/2026
Netpbm before 10.86.51, 11.x before 11.02.30, and 11.03 before 11.15.08 contains a stack-based buffer overflow in the picttoppm paintPoly() function due to an unbounded polygon point count. Attackers can supply a crafted PICT file with a polygon exceeding 100 points to overwrite the fixed pts array, causing crashes or potentially code execution.
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Analysis
by VulDB Data Team • 11/02/2026
The vulnerability identified in Netpbm versions prior to 10.86.51, 11.x before 11.02.30, and 11.03 before 11.15.08 represents a critical stack-based buffer overflow within the picttoppm utility's paintPoly function. This flaw stems from an insufficient validation of input data specifically regarding the count of polygon points defined in PICT files. When processing these graphics files, the application allocates a fixed-size array on the stack to store point coordinates but fails to verify that the number of points specified in the file header does not exceed the capacity of this allocated buffer. This lack of bounds checking allows an attacker to craft a malicious PICT file containing a polygon definition with more than one hundred points, thereby triggering the overflow condition when the application attempts to copy these values into the fixed array.
From a technical perspective, this vulnerability is classified under CWE-121, which denotes stack-based buffer overflow. The mechanism involves writing data beyond the boundaries of the allocated memory space on the call stack, overwriting adjacent memory locations that may contain critical control information such as return addresses or frame pointers. In the context of Netpbm, a widely used toolkit for image manipulation and conversion, this flaw is particularly dangerous because PICT files are often processed in automated pipelines where user-supplied input might be trusted implicitly. The specific threshold mentioned, exceeding one hundred points, indicates that even moderately complex but valid-looking graphics can trigger the exploit condition if crafted with malicious intent to target the memory layout of the running process.
The operational impact of this vulnerability is severe, ranging from denial of service to arbitrary code execution. If an attacker successfully exploits the buffer overflow by carefully crafting the payload to overwrite specific stack locations, they can hijack the control flow of the application. This could lead to remote code execution with the privileges of the user running the Netpbm utility. Even in cases where precise exploitation for code execution is difficult due to modern memory protection mechanisms like ASLR or DEP, the vulnerability reliably causes crashes and segmentation faults, resulting in a denial of service against services that rely on image processing capabilities. This disrupts workflows involving automated image conversion, rendering, or analysis tasks that ingest external graphic files.
Mitigation strategies primarily involve upgrading to patched versions of Netpbm where this issue has been resolved through proper input validation and bounds checking within the paintPoly function. Organizations relying on older versions should implement strict file type filtering and size limits for incoming PICT files as a temporary countermeasure. Additionally, deploying network intrusion detection systems that can identify anomalous patterns in image processing traffic may help detect attempted exploitation. It is also advisable to run such utilities with restricted privileges using least-privilege principles to limit the potential impact of any successful compromise. The vulnerability aligns with ATT&CK techniques related to initial access and execution via crafted files, emphasizing the need for robust input sanitization in all image processing software components.