CVE-2025-27832: Artifex Ghostscript Buffer Overflow Flaw

CVE-2025-27832 Overview

A critical buffer overflow vulnerability has been identified in Artifex Ghostscript before version 10.05.0. The vulnerability exists in the NPDL (Nippon Page Description Language) device driver implementation within contrib/japanese/gdevnpdl.c. This buffer overflow in the Compression buffer can be exploited by a remote attacker to potentially execute arbitrary code or cause a denial of service condition.

Critical Impact

Remote attackers can exploit this buffer overflow vulnerability in the NPDL device compression handling to potentially achieve code execution, compromise system confidentiality, integrity, and availability without requiring any user interaction or privileges.

Affected Products

• Artifex Ghostscript versions prior to 10.05.0
• Systems utilizing the NPDL device driver for Japanese printer support
• Applications and services that process PostScript or PDF files using vulnerable Ghostscript installations

Discovery Timeline

• 2025-03-25 - CVE-2025-27832 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-27832

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a classic buffer overflow. The flaw resides in the NPDL device driver, which is part of the Japanese printer driver contributions in Ghostscript. The NPDL device handles page description output for certain Japanese printers and includes compression functionality that fails to properly validate buffer boundaries during data processing operations.

The buffer overflow occurs in the compression handling code within contrib/japanese/gdevnpdl.c. When processing specially crafted input, the compression routine can write beyond the allocated buffer boundaries, leading to memory corruption. This can be triggered when Ghostscript processes a malicious PostScript or PDF document that targets the NPDL output device.

Root Cause

The root cause of this vulnerability is insufficient bounds checking in the compression buffer handling within the NPDL device driver. The gdevnpdl.c source file implements compression functionality for the NPDL output format, but fails to properly validate that data being written to the compression buffer does not exceed its allocated size. This classic buffer overflow pattern allows an attacker to corrupt adjacent memory regions.

Attack Vector

The attack vector for this vulnerability is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by:

1. Crafting a malicious PostScript or PDF document containing specially designed content
2. Tricking a victim into processing the document through Ghostscript with NPDL output enabled, or targeting a server-side document processing service
3. When the vulnerable compression code processes the malicious input, the buffer overflow is triggered
4. The attacker can potentially achieve arbitrary code execution by controlling the overwritten memory contents

The vulnerability can be exploited through any application or service that uses Ghostscript to process untrusted documents. This includes web applications, document conversion services, print servers, and preview generators that may invoke Ghostscript with NPDL device output.

The vulnerability manifests in the compression buffer handling within contrib/japanese/gdevnpdl.c. When the NPDL device driver processes document data, insufficient bounds checking allows writes beyond the allocated compression buffer. For technical implementation details, refer to the Ghostscript Bug Report #708133.

Detection Methods for CVE-2025-27832

Indicators of Compromise

• Unexpected crashes or segmentation faults in Ghostscript processes during document processing
• Anomalous memory access patterns or memory corruption errors in Ghostscript logs
• Presence of malformed PostScript or PDF files that specifically target NPDL device output
• Unexpected child processes spawned by Ghostscript instances

Detection Strategies

• Monitor Ghostscript process behavior for signs of exploitation such as abnormal memory usage or unexpected system calls
• Implement file integrity monitoring for Ghostscript binaries and configuration files
• Deploy endpoint detection rules to identify suspicious PostScript or PDF documents being processed
• Use application sandboxing to limit the impact of potential exploitation

Monitoring Recommendations

• Enable verbose logging for Ghostscript operations to capture error conditions and crashes
• Implement network traffic analysis to detect suspicious document transfers to systems running Ghostscript
• Configure security monitoring to alert on Ghostscript process crashes or abnormal terminations
• Monitor system logs for evidence of memory corruption or exploitation attempts

How to Mitigate CVE-2025-27832

Immediate Actions Required

• Upgrade Artifex Ghostscript to version 10.05.0 or later immediately
• If immediate patching is not possible, disable the NPDL device driver if it is not required for operations
• Implement network segmentation to limit exposure of systems running vulnerable Ghostscript versions
• Restrict Ghostscript from processing untrusted documents until patched

Patch Information

Artifex has addressed this vulnerability in Ghostscript version 10.05.0. Organizations should upgrade to this version or later to remediate the vulnerability. The fix addresses the buffer overflow in the NPDL device compression handling by implementing proper bounds checking.

For detailed patch information, refer to the Ghostscript Bug Report #708133. Additionally, the Debian LTS Announce Notice provides information on patched packages for Debian-based systems.

Workarounds

• Disable the NPDL device driver by removing or renaming the device library if Japanese printer support is not required
• Run Ghostscript with -dSAFER flag to enable sandbox mode and restrict file operations
• Use Ghostscript's -dNODISPLAY option and avoid specifying NPDL as the output device for untrusted documents
• Implement input validation to filter or quarantine suspicious PostScript and PDF documents before processing

# Configuration example - Disable NPDL device and enable safer mode
# Add these options when invoking Ghostscript for untrusted documents
ghostscript -dSAFER -dBATCH -dNOPAUSE -sDEVICE=pdfwrite input.ps

# Alternatively, restrict available devices at compile time
# or remove gdevnpdl.so/gdevnpdl.dll from the Ghostscript installation