Critical Ghostscript Vulnerability CVE-2026-39919 Turns Uploaded PDFs Into Remote Code Execution

TL;DR

Artifex released Ghostscript 10.08.0 on September 8, 2026, fixing a critical heap buffer overflow rated CVSS 9.8. Wordfence found the Ghostscript vulnerability and turned a crafted PDF into unauthenticated remote code execution on a test WordPress site. Site owners must update the system package, since no WordPress plugin update exists.

The Wordfence Threat Intelligence team discovered the bug with its Wordfence Argus tool during a WordPress 7.1 assessment. Researcher Alex Thomas led and validated the work. Wordfence detailed the findings in its report.

Why It Matters

Ghostscript reads PDF and PostScript files and turns their pages into images. Many servers run it without their owners knowing. On WordPress, the chain runs through Imagick and ImageMagick whenever the site builds a PDF preview or thumbnail.

The reach goes well beyond WordPress. “This is not a WordPress-only vulnerability,” Wordfence stresses. Document management systems, print services, invoice processors, mail gateways and conversion APIs can all pass untrusted PDFs to Ghostscript.

Fixing it also works differently from a typical WordPress bug. As Wordfence puts it, “If you run a WordPress site, there isn’t a WordPress plugin to update.” Instead, the fix arrives through the operating system or the container image.

How serious is the risk?

The CVE record assigns a CVSS 3.1 score of 9.8 and a CVSS 4.0 score of 9.3. Still, Wordfence urges a measured view: “You should patch it, but the score describes a worst case rather than a guarantee.”

Wordfence built two working exploits for its lab build. Next, it ran them 10,240 times across ten other Linux package environments. Neither succeeded once outside the matching build. However, the same exploit kept working across four setups that shared the exact Ghostscript executable.

That result points to targeted attacks and shared hosting images as the main risk. In Wordfence’s words, “Build-specific exploitation is harder, not harmless.”

How the Attack Works

The flaw sits in the code Ghostscript uses to decode JPEG 2000 images inside PDFs. A crafted PDF can make Ghostscript write data past the end of a memory buffer. That corruption can then lead to code execution with the permissions of the account processing the file.

Notably, the file looks harmless to ordinary checks. File extension, MIME type and basic structure checks do not catch it. Ghostscript’s -dSAFER sandbox does not stop it either. “Do not treat -dSAFER as a fix,” Wordfence warns.

Who is exposed on WordPress

A WordPress site is at risk only when all four conditions apply:

• Visitors or low-privileged users can upload a PDF.
• The site then creates a preview or thumbnail of that PDF.
• The server uses Imagick or another tool that calls Ghostscript.
• The installed Ghostscript package lacks the fix.

The official WordPress Docker image snapshot that Wordfence tested was vulnerable. Even so, stock WordPress does not let anonymous visitors upload PDFs. An attacker would need a plugin, form or account that opens that path.

Exploitation status

No exploitation in the wild has been confirmed. Wordfence states it has “found no public evidence that it is being exploited today.” A minimal crash test case is public, but Wordfence’s code-execution exploits are not.

Affected Versions

The flaw affects Ghostscript 9.21 through 10.07.1 when the OpenJPEG decoder is present. Artifex fixed it in 10.08.0. Note that the 10.08.0 release candidate also reports version 10.08.0 but remains vulnerable.

Distribution status varies. Ubuntu has fixed 22.04, 24.04 and 26.04. The Debian security tracker lists Debian 13 as fixed through its security repository, while Debian 12 remains vulnerable. AlmaLinux 10 shipped its fix on October 2.

Patch and Mitigation Steps

• Install the fixed Ghostscript package from your operating system or host.
• Check the full package revision, not just “gs –version,” because distributions often backport fixes.
• Rebuild containers from an updated base image instead of restarting old ones.
• Ask your managed host whether its Ghostscript package includes the CVE-2026-39919 fix.

If you cannot patch right away, Wordfence suggests these stopgaps:

• Stop accepting PDFs from visitors and low-privileged users.
• Disable PDF reads in ImageMagick’s security policy.
• Limit files per submission and rate limit upload forms.
• Run document conversion in a separate, locked-down service.

Artifex confirmed the report one day after Wordfence filed it. The original Ghostscript bug report tracks the fix. Patching remains the only complete answer to this Ghostscript vulnerability.

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Written by

@DdoS · Security Researcher

Do Son

Do Son is the Founder and Editor of SecurityOnline.info. Working in cybersecurity since 2013, he reports on vulnerabilities, malware, and emerging threats, providing timely analysis to help organizations and individuals stay ahead of evolving risks.