CVE-2026-101258: Ghostscript Sandbox Bypass RCE Vulnerability

CVE-2026-101258 Overview

A flaw in Ghostscript allows attackers to bypass the -dSAFER sandbox and execute arbitrary shell commands through crafted PostScript or EPS documents. The vulnerability chains memory corruption during document parsing with runtime disabling of internal path access controls. Attackers can deliver malicious documents directly or through workflows that delegate rendering to Ghostscript, such as EPS import or print conversion pipelines. Successful exploitation compromises confidentiality, integrity, and availability of data accessible to the Ghostscript process. The flaw is tracked under CWE-787 (Out-of-Bounds Write).

Critical Impact

A single crafted PostScript or EPS file can escape the Ghostscript sandbox and run arbitrary shell commands under the privileges of the rendering process.

Affected Products

• Ghostscript (PostScript and EPS rendering engine)
• Applications and server workflows that invoke Ghostscript for EPS import or print conversion
• Linux distributions bundling vulnerable Ghostscript packages (see Red Hat CVE-2026-101258)

Discovery Timeline

• 2026-10-06 - CVE-2026-101258 published to NVD
• 2026-10-07 - Last updated in NVD database

Technical Details for CVE-2026-101258

Vulnerability Analysis

The flaw combines two primitives inside Ghostscript. The first is an out-of-bounds write during parsing of crafted PostScript or EPS content. The second is a runtime bypass of the -dSAFER sandbox, which normally restricts file and command access during rendering.

By chaining these primitives, an attacker overwrites parser state and disables the internal path access controls that -dSAFER relies on. Once the sandbox check is neutralized, the attacker reaches Ghostscript operators that can spawn shell commands. The result is arbitrary command execution in the context of the Ghostscript process.

The local attack vector reflects that the malicious document must reach the renderer, but automated pipelines effectively convert this into a document-driven attack. User interaction is required when a document is opened, imported, or converted.

Root Cause

The root cause is an out-of-bounds write [CWE-787] in Ghostscript's document parsing path. The parser fails to validate boundary conditions on attacker-controlled structures, allowing adjacent state to be corrupted. That corruption clears or redirects the flags enforcing -dSAFER, breaking the trust boundary between untrusted document content and privileged interpreter operators.

Attack Vector

An attacker crafts a PostScript or EPS document that triggers the memory corruption during normal rendering. The document can be delivered directly to a user, embedded in a container format that invokes Ghostscript, or supplied to a server-side conversion workflow. When the document is rendered, the corruption disables sandbox enforcement and the embedded operators execute shell commands under the Ghostscript process account.

A proof-of-concept is published in the GitHub PoC for Ghostscript repository. See the Red Hat Bug Report #2542396 for additional technical context.

Detection Methods for CVE-2026-101258

Indicators of Compromise

• Ghostscript (gs) processes spawning shell interpreters such as /bin/sh, /bin/bash, or cmd.exe.
• Unexpected child processes of print spoolers, EPS converters, or document pipelines that invoke Ghostscript.
• PostScript or EPS files containing suspicious operators referencing %pipe%, .libfile, or raw shell strings.
• Outbound network connections initiated by the Ghostscript process immediately after document rendering.

Detection Strategies

• Alert on process-tree anomalies where gs is the parent of shell, scripting, or network utilities.
• Hunt for file-write and execve activity by the Ghostscript process outside expected output directories.
• Inspect EPS and PostScript inputs on gateways for operators that attempt filesystem or pipe access.

Monitoring Recommendations

• Collect endpoint process telemetry and command-line arguments for all Ghostscript invocations.
• Monitor server-side conversion workflows (print services, CMS uploaders, image pipelines) for Ghostscript child-process behavior.
• Correlate document ingestion events with subsequent outbound connections or privilege-sensitive file access.

How to Mitigate CVE-2026-101258

Immediate Actions Required

• Inventory systems running Ghostscript, including indirect usage by ImageMagick, CUPS, LibreOffice, and server-side converters.
• Apply distribution-provided Ghostscript updates as soon as they become available via vendor channels.
• Restrict ingestion of untrusted PostScript and EPS documents at email, web, and file-share boundaries.
• Run Ghostscript under a dedicated low-privilege account with no shell or network capabilities.

Patch Information

At publication, vendor advisories are tracked through Red Hat CVE-2026-101258 and Red Hat Bug Report #2542396. Apply the fixed Ghostscript packages shipped by your Linux distribution or software vendor. Verify installed versions after patching and restart dependent services such as CUPS, ImageMagick workers, and document conversion daemons.

Workarounds

• Disable automatic EPS and PostScript rendering in applications that delegate to Ghostscript until patches are deployed.
• Convert incoming PostScript and EPS files to safer formats in an isolated sandbox or container before downstream processing.
• Enforce AppArmor, SELinux, or seccomp profiles that deny execve of shell interpreters from the Ghostscript binary.
• Remove Ghostscript from systems that do not require PostScript or PDF rendering.

# Example AppArmor-style restriction concept for the Ghostscript binary
# Deny shell execution and restrict filesystem writes to a dedicated output directory
/usr/bin/gs {
    deny /bin/** x,
    deny /usr/bin/sh x,
    deny /usr/bin/bash x,
    /var/spool/gs-output/** rw,
    network inet stream,
}