CVE-2019-3838 in Ghostscript
Summary
by MITRE
It was found that the forceput operator could be extracted from the DefineResource method in ghostscript before 9.27. A specially crafted PostScript file could use this flaw in order to, for example, have access to the file system outside of the constrains imposed by -dSAFER.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/17/2025
The vulnerability identified as CVE-2019-3838 represents a critical privilege escalation flaw within the Ghostscript PDF rendering engine that affected versions prior to 9.27. This vulnerability resides in the forceput operator implementation within the DefineResource method, which serves as a fundamental component in PostScript processing. The flaw allows attackers to bypass security restrictions that are normally enforced by the -dSAFER parameter, which is designed to prevent unauthorized file system access during document processing. This weakness directly undermines the sandboxing mechanisms that Ghostscript employs to isolate potentially malicious content from the underlying operating system.
The technical exploitation of this vulnerability leverages the improper handling of the forceput operator within the DefineResource method to manipulate the internal state of the PostScript interpreter. When processing a specially crafted PostScript file, an attacker can construct sequences that manipulate the operator table and forceput functionality to extract or modify system-level resources. This manipulation enables the bypass of the -dSAFER security constraint, which typically restricts file system access to only the directories specified by the -dSAFER parameter. The vulnerability essentially allows an attacker to elevate their privileges beyond the intended security boundaries, potentially enabling arbitrary file read/write operations, directory traversal, and system reconnaissance.
The operational impact of CVE-2019-3838 is significant across multiple attack vectors and threat scenarios. In web environments where Ghostscript is used for PDF processing, this vulnerability could enable remote code execution through malicious document uploads, particularly in applications that process untrusted PDF content without proper sanitization. The vulnerability is particularly dangerous in server environments where Ghostscript is used for document conversion, rendering, or processing of user-uploaded content, as it could allow attackers to access sensitive system files, exfiltrate data, or establish persistent access through file system manipulation. This vulnerability aligns with CWE-276, which describes improper privileges and access control issues in software systems. The attack surface is further expanded through the ATT&CK framework's privilege escalation techniques, specifically targeting the T1068 privilege escalation method where adversaries leverage software vulnerabilities to gain elevated system privileges.
Mitigation strategies for CVE-2019-3838 primarily focus on immediate version upgrades to Ghostscript 9.27 or later, which contain the necessary patches to address the forceput operator handling within the DefineResource method. Organizations should implement comprehensive patch management protocols to ensure all systems utilizing Ghostscript are updated promptly. Additionally, administrators should enforce strict file system access controls and limit the execution environment of Ghostscript processes to minimal required permissions. Network segmentation and monitoring should be implemented to detect potential exploitation attempts, particularly when processing untrusted PostScript or PDF content. Security configurations should include disabling unnecessary features and ensuring that the -dSAFER parameter is properly enforced in all processing environments. The vulnerability demonstrates the importance of proper operator table management and the need for robust sandboxing mechanisms in interpreted language processors, aligning with security best practices outlined in NIST SP 800-144 for secure software development and vulnerability management.