CVE-2026-120434 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 picttoppm's scanPoly() function in converter/ppm/picttoppm.c. Attackers can supply a crafted PICT file whose polygon edges produce more than 5000 points, overflowing the coord stack array to crash the converter or potentially execute code.
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Analysis
by VulDB Data Team • 11/02/2026
The vulnerability identified as CVE-2019-13768 resides within the Netpbm image processing suite, specifically affecting versions prior to 10.86.51, 11.x prior to 11.02.30, and 11.03 prior to 11.15.08. This flaw is located in the picttoppm converter utility, which is responsible for translating PICT image files into the Portable Pixmap format. The core technical issue stems from a stack-based buffer overflow within the scanPoly function found in the source file converter/ppm/picttoppm.c. During the parsing and processing of polygon data embedded within a PICT file, the application fails to adequately validate the number of points defining the polygon edges before allocating or utilizing memory on the call stack.
When an attacker supplies a maliciously crafted PICT file containing polygons with more than 5000 edge points, the coordinate array exceeds its allocated buffer size. This overflow overwrites adjacent data on the stack, including return addresses and other critical control flow information. The immediate operational impact of this memory corruption is typically a segmentation fault or application crash, resulting in a denial-of-service condition for users attempting to process such files. However, given that the vulnerability involves arbitrary write capabilities via stack manipulation, it presents a significant risk for remote code execution if an attacker can precisely craft the overflow payload to overwrite function pointers with shellcode addresses.
From a classification perspective, this flaw aligns with CWE-121, which denotes a stack-based buffer overflow resulting from insufficient bounds checking on user-supplied input that is copied into a fixed-size stack buffer. The attack vector leverages CWE-20, improper input validation, as the application accepts external data without verifying its structural integrity or size constraints prior to processing. In terms of tactical behavior, this vulnerability maps to MITRE ATT&CK technique T1203, exploitation for defense evasion, and potentially T1059 if used in conjunction with command execution payloads during an intrusion sequence. The lack of robust input sanitization allows the application to be tricked into executing unintended operations through memory corruption rather than logical errors.
Mitigation strategies primarily involve upgrading the Netpbm installation to version 10.86.51 or later, specifically targeting versions 11.02.30 and 11.15.08 for their respective branches where these fixes were officially patched. For environments unable to upgrade immediately, deploying input validation mechanisms at the network perimeter can help filter out malformed PICT files before they reach the vulnerable application layer. Additionally, enabling stack protection features such as Stack Canaries or Address Space Layout Randomization in the operating system configuration can mitigate the likelihood of successful code execution by making it more difficult for attackers to predict memory layouts and overwrite critical control data effectively.