ImageMagick image processing can read or write application files
Web applications that use ImageMagick to process uploaded or otherwise untrusted images face arbitrary file read and write vulnerabilities when dangerous coders or delegates remain enabled. The CERT vulnerability note was updated on November 12, 2026, and says an attacker may exploit crafted SVG or PostScript content to access files available to the ImageMagick process.
The affected workflow includes image uploads and automated processing in applications such as Ruby on Rails, WordPress, MediaWiki, ownCloud Classic and Redmine, according to CERT. The note says ImageMagick is used for tasks including thumbnail generation, cropping, conversion and transformation, so exposure depends on whether the application passes attacker-controlled content to the image processor.
The SVG variant can use an image element to invoke the MSL coder, which lets a crafted file act as a Magick Scripting Language script. A separate variant can cause ImageMagick to identify crafted input as PostScript and invoke Ghostscript, with the reported configuration permitting access within /tmp. CERT says the resulting file access can affect uploaded files, processing artifacts, sessions and other sensitive data stored there.
CERT recommends an allowlist-based policy.xml that enables only the formats and operations the application needs. Its guidance specifically says to disable unnecessary coders and delegates, including MSL, MVG, PS, EPS and PDF, and to verify that the effective policy rejects prohibited formats. Updating ImageMagick alone may not remove the exposure if the deployed policy still permits dangerous processing.
Operators should also process untrusted images in a dedicated, minimally privileged environment with restricted filesystem access, according to the note. The same controls apply to image preprocessing and post-processing in AI pipelines. Writable host mounts, shared volumes, credentials and inference artifacts can increase the impact if an attacker gains file access.
The Rails team shipped versions 8.0.5.2 and 8.1.4.1 with a policy.xml file for Active Storage's use of mini_magick. The note says ownCloud Classic and the Kiteworks platform are affected and that fixes are being implemented, while Wikimedia Foundation reported that MediaWiki is not affected. CERT said there was no indication of exploitation when the note was updated.