CVE-2025-27831: Ghostscript Buffer Overflow Vulnerability

CVE-2025-27831 Overview

CVE-2025-27831 is a critical buffer overflow vulnerability discovered in Artifex Ghostscript before version 10.05.0. The vulnerability exists within the DOCXWRITE and TXTWRITE device implementations, specifically in the devices/vector/doc_common.c file. When processing documents containing excessively long characters, the text buffer can overflow, potentially allowing attackers to execute arbitrary code or cause denial of service conditions.

Critical Impact

This buffer overflow vulnerability in Ghostscript's document writing functionality can be exploited remotely without authentication, potentially leading to complete system compromise through arbitrary code execution with the privileges of the Ghostscript process.

Affected Products

• Artifex Ghostscript versions prior to 10.05.0
• Systems using Ghostscript for document conversion (DOCX, TXT output)
• Applications and services that process untrusted PostScript or PDF files through Ghostscript

Discovery Timeline

• 2025-03-25 - CVE-2025-27831 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-27831

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input), a classic buffer overflow condition. The flaw resides in the document writing components of Ghostscript, specifically affecting how the DOCXWRITE and TXTWRITE output devices handle character data during document conversion operations.

When Ghostscript processes input documents and converts them to DOCX or TXT formats, it utilizes internal text buffers to temporarily store character sequences. The vulnerable code path in devices/vector/doc_common.c fails to properly validate the length of character data before copying it into a fixed-size buffer. An attacker can craft a malicious document containing specially formatted long character sequences that exceed the buffer boundaries.

The network attack vector combined with no required privileges or user interaction makes this vulnerability particularly dangerous in environments where Ghostscript processes documents from untrusted sources, such as print servers, document conversion services, or web applications that generate PDF previews.

Root Cause

The root cause of CVE-2025-27831 is insufficient bounds checking in the text buffer handling code within devices/vector/doc_common.c. When the DOCXWRITE or TXTWRITE devices process character data, the implementation fails to verify that incoming character sequences will fit within the allocated buffer space before performing the copy operation. This allows specially crafted input to write beyond the buffer boundaries, corrupting adjacent memory.

Attack Vector

Exploitation of this vulnerability can occur through any workflow where Ghostscript processes attacker-controlled documents. Common attack scenarios include:

The attacker crafts a malicious PostScript, PDF, or other Ghostscript-supported document format containing carefully constructed long character sequences. When this document is processed by a vulnerable Ghostscript instance configured to output DOCX or TXT format, the overflow condition triggers. Depending on the memory layout and system protections in place, this can lead to code execution, denial of service, or information disclosure.

Attack surfaces include document conversion web services, print spoolers, email attachment processors, and any application that invokes Ghostscript to render or convert documents from untrusted sources. For detailed technical information, refer to the Ghostscript Bug Report #708132.

Detection Methods for CVE-2025-27831

Indicators of Compromise

• Unexpected Ghostscript process crashes or termination, particularly when processing documents with DOCXWRITE or TXTWRITE output devices
• Anomalous memory consumption or segmentation faults in gs processes
• Suspicious document files containing unusually long text sequences or malformed character data
• Evidence of exploitation attempts in application logs showing Ghostscript errors during document conversion

Detection Strategies

• Monitor Ghostscript process behavior for abnormal memory access patterns or unexpected termination signals (SIGSEGV, SIGABRT)
• Implement file integrity monitoring on systems running Ghostscript to detect potential post-exploitation modifications
• Deploy network-based detection rules to identify documents with suspicious character sequences targeting document output devices
• Utilize SentinelOne's Singularity platform for real-time behavioral analysis of Ghostscript processes and automatic threat detection

Monitoring Recommendations

• Enable verbose logging for Ghostscript operations and monitor for errors related to buffer operations in doc_common.c
• Configure SentinelOne agents to alert on suspicious process behavior patterns associated with buffer overflow exploitation
• Implement application sandboxing for Ghostscript processes to limit the impact of potential exploitation
• Regularly audit systems for Ghostscript version information and flag installations running versions prior to 10.05.0

How to Mitigate CVE-2025-27831

Immediate Actions Required

• Upgrade Artifex Ghostscript to version 10.05.0 or later immediately on all affected systems
• Audit all systems and applications that utilize Ghostscript for document processing and prioritize patching based on exposure
• Implement input validation and document sanitization before processing untrusted files through Ghostscript
• Consider disabling DOCXWRITE and TXTWRITE devices if they are not required for your use case until patching is complete

Patch Information

Artifex has addressed this vulnerability in Ghostscript version 10.05.0. Organizations should update to this version or later to remediate the vulnerability. The fix implements proper bounds checking for character data in the document writing code path.

For systems managed through package managers, check for updated packages. Debian users should refer to the Debian LTS Announcement April 2025 for distribution-specific update information. The official bug tracking information is available at the Ghostscript Bug Report #708132.

Workarounds

• Restrict Ghostscript processing to trusted documents only until patches can be applied
• Run Ghostscript in a sandboxed environment (containers, VMs, or application sandboxes) to limit exploitation impact
• Disable the DOCXWRITE and TXTWRITE output devices by modifying Ghostscript's device configuration if these features are not required
• Implement network segmentation to isolate document processing systems from critical infrastructure

# Example: Check Ghostscript version and verify patched status
gs --version
# Should return 10.05.0 or later

# Example: Restrict Ghostscript to safer operation modes
# Disable potentially vulnerable devices by limiting output devices
gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=output.pdf input.ps