CVE-2019-3839 in Ghostscript
Summary
by MITRE
It was found that in ghostscript some privileged operators remained accessible from various places after the CVE-2019-6116 fix. 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. Ghostscript versions before 9.28 are vulnerable.
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Analysis
by VulDB Data Team • 06/17/2025
The vulnerability identified as CVE-2019-3839 represents a critical security regression in the Ghostscript PDF rendering engine that emerged following the remediation of CVE-2019-6116. This flaw demonstrates how security patches can inadvertently create new attack vectors when not thoroughly vetted for side effects. The vulnerability specifically affects Ghostscript versions prior to 9.28, indicating that the software maintainers had already identified and addressed the broader issue in version 9.28 and subsequent releases. The core problem lies in the persistence of certain privileged operators that should have been completely restricted after the previous fix, creating a pathway for unauthorized system access.
The technical nature of this vulnerability stems from the improper handling of privilege separation within Ghostscript's PostScript interpreter. When processing specially crafted PostScript files, attackers could exploit the lingering access to privileged operators that were meant to be disabled following the CVE-2019-6116 remediation. This regression allowed malicious code to bypass the -dSAFER sandboxing mechanism, which is designed to prevent file system access outside of specified directories. The flaw essentially creates a backdoor through which arbitrary file system operations could be performed, potentially enabling attackers to read, write, or execute files on the host system without proper authorization.
The operational impact of CVE-2019-3839 extends beyond simple privilege escalation, as it fundamentally undermines the security model that Ghostscript employs to isolate processing environments. This vulnerability could be exploited in numerous scenarios including web-based PDF processing, email attachment handling, and document conversion services where Ghostscript is used as a backend component. The implications are particularly severe in environments where Ghostscript processes untrusted input from external sources, as it could enable attackers to access sensitive system files, exfiltrate data, or establish persistent access through file system manipulation. The vulnerability aligns with CWE-276, which addresses improper privilege management, and represents a classic example of how security controls can be circumvented through incomplete patch implementation.
Mitigation strategies for CVE-2019-3839 require immediate deployment of Ghostscript version 9.28 or later, which contains the comprehensive fix for this vulnerability. Organizations should also implement additional defensive measures including strict input validation for PostScript and PDF files, network segmentation to limit access to systems running Ghostscript, and monitoring for suspicious file system activity. The remediation process should include thorough testing of updated systems to ensure that the privilege separation mechanisms function correctly. Security teams should also consider implementing sandboxing solutions that provide additional isolation layers beyond the built-in -dSAFER protection, as recommended by ATT&CK technique T1059.007 for PostScript and scripting languages. Organizations using Ghostscript in production environments must conduct comprehensive vulnerability assessments to identify any potential exploitation attempts and establish incident response procedures specifically tailored to address this type of privilege escalation vulnerability.