CVE-2026-77467: Lychee: A single 383-byte PDF causes ~184 seconds of CPU consumption in the real processing path
Lychee is a free, open-source photo-management tool. Prior to 7.7.0, Lychee enables ImageMagick PDF support with Ghostscript but does not apply an effective pre-render limit to PDF page dimensions in ImagickHandler::loadPdf(). An authenticated user who can upload a small PDF with an oversized /MediaBox can cause Imagick::readImage() to consume substantial CPU before failing to produce an image. When QUEUECONNECTION selects synchronous processing the request can occupy a web worker, while the official asynchronous Docker configuration can clog the shared image-processing queue and delay other work. The advisory did not identify a Ghostscript sandbox escape. This issue is fixed in version 7.7.0.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Lycheeto a version that resolves this vulnerability.Fixed in 7.7.0
Event History
Frequently Asked Questions
Who can exploit this issue?
An authenticated user who is permitted to upload PDFs can trigger the excessive CPU consumption by uploading a small PDF with an oversized /MediaBox. The advisory does not describe exploitation by unauthenticated users.
Are default deployments affected, and what is the operational impact?
Affected deployments have ImageMagick PDF support enabled with Ghostscript. With synchronous queue processing, a crafted upload can occupy a web worker; with the official asynchronous Docker configuration, it can clog the shared image-processing queue and delay other work.
Is this a Ghostscript sandbox escape?
No Ghostscript sandbox escape was identified in the advisory. The described impact is resource consumption during PDF rendering before image creation fails.
What versions are affected and how can the issue be remediated?
Lychee versions prior to 7.7.0 are affected. Upgrade to version 7.7.0, which applies an effective pre-render limit to PDF page dimensions.