CVE-2026-103226: 
Ghostscript vulnerability analysis and mitigation

CVE-2026-103226 is a stack-based buffer overflow vulnerability in Artifex Ghostscript affecting versions up to and including 10.09.0. The flaw resides in the type1_callsubr function within devices/vector/gdevpsfx.c in the Pdfwrite component, triggered during Type 1 font processing. It was published on September 30, 2026, and a patch has been made available. The vulnerability carries a CVSS v3.1 base score of 6.3 (Medium) and a CVSS v4.0 base score of 2.1 (Low), with an EPSS score of approximately 0.44% (Red Hat Advisory, GitHub Advisory).

The root cause is a stack-based buffer overflow (CWE-121, CWE-787, CWE-119) in the type1_callsubr function of Ghostscript's Pdfwrite component (devices/vector/gdevpsfx.c), triggered when processing maliciously crafted Type 1 font data embedded in a document such as a PDF. An attacker can exploit this remotely by delivering a specially crafted file to a victim, who must open or process it with a vulnerable Ghostscript instance — requiring passive user interaction. The fix was implemented by applying a defined macro in the font parsing loop rather than in the callsubr function itself, better aligning with standard usage patterns. A proof-of-concept exploit attachment is referenced in the Ghostscript bug tracker (Red Hat Bugzilla, GitHub Advisory).

Successful exploitation could allow an unauthenticated remote attacker to crash the Ghostscript application (denial of service) or potentially execute arbitrary code with the privileges of the user or service running Ghostscript, resulting in partial compromise of confidentiality, integrity, and availability. The impact is constrained to the vulnerable system itself, with no subsequent system impact identified. In environments where Ghostscript is used as a backend for document processing services (e.g., web-based PDF converters or print servers), exploitation could affect multiple users or enable further lateral movement if the service runs with elevated privileges (Red Hat Advisory, GitHub Advisory).

A proof-of-concept exploit attachment is publicly referenced in the Ghostscript bug tracker (attachment ID 28495), though no weaponized exploit kit or active in-the-wild exploitation has been confirmed as of the latest available data. The EPSS score is approximately 0.44% (37th percentile), indicating a relatively low near-term exploitation probability. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, and no threat actor attribution has been reported. Exploitation requires user interaction (passive), meaning a victim must process a malicious file (GitHub Advisory, Red Hat Bugzilla).

1. Craft a malicious file: Create a specially crafted PDF or PostScript document containing malformed Type 1 font data designed to trigger a stack-based buffer overflow in the type1_callsubr function of Ghostscript's Pdfwrite component (devices/vector/gdevpsfx.c).
2. Deliver the payload: Distribute the malicious file to a target via email attachment, file sharing, or by hosting it on a web page — exploiting any vector that causes the victim to open or process the file with a vulnerable Ghostscript instance (version ≤ 10.09.0).
3. Trigger processing: The victim (or an automated service such as a document converter or print server) processes the file using Ghostscript, causing the vulnerable type1_callsubr function to be invoked with attacker-controlled font data.
4. Overflow the stack buffer: The malformed font data causes an out-of-bounds write on the stack, potentially overwriting the return address or other control-flow data.
5. Achieve code execution or crash: Depending on exploit precision and target environment mitigations (e.g., ASLR, stack canaries), the attacker may achieve arbitrary code execution with the privileges of the Ghostscript process, or at minimum cause a denial of service (Red Hat Bugzilla, GitHub Advisory).

• File System: Unexpected or suspicious PDF/PostScript files delivered to systems running Ghostscript; files with anomalous or deeply nested Type 1 font structures.
• Process: Ghostscript process (gs) crashing unexpectedly or spawning unusual child processes (e.g., shells, network utilities); core dump files generated by the Ghostscript process.
• Logs: Application or system logs showing Ghostscript segmentation faults or abnormal termination when processing specific files; repeated processing failures on the same document.
• Network: Outbound connections from the Ghostscript process or its parent service to unexpected external IP addresses, which may indicate post-exploitation activity if code execution is achieved.

Artifex has released a patch addressing this vulnerability by modifying the font parsing logic in the Pdfwrite component; users should update Ghostscript to a version beyond 10.09.0 that includes this fix. As a workaround, restrict Ghostscript from processing untrusted PDF or PostScript files, and run Ghostscript in a sandboxed environment with minimal privileges (e.g., using -dSAFER mode and OS-level sandboxing). Organizations using Ghostscript as a backend for document processing services should implement strict input validation and avoid exposing the service to untrusted file uploads until patched (Red Hat Bugzilla, GitHub Advisory).

Coverage of CVE-2026-103226 has been limited to vulnerability tracking platforms and security news aggregators. TechJuice published an article noting that Ghostscript flaws could allow attackers to hijack servers via PDF uploads, highlighting the risk to document processing pipelines. No significant vendor statements beyond the patch advisory or notable researcher commentary have been identified at this time.