CVE-2026-77467
Deferred Deferred - Pending Action

Remote Code Execution via PDF Processing in Lychee

Publication date: 2026-10-15

Last updated on: 2026-10-15

Assigner: GitHub, Inc.

Description
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 QUEUE_CONNECTION 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.

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Meta Information

Published
2026-10-15
Last Modified
2026-10-15
Generated
2026-10-19
AI Q&A
2026-10-15
EPSS Evaluated
2026-10-18
NVD
CVE-2026-77467
EUVD
EUVD-2026-102194

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
LycheeOrg Lychee < 7.7.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.

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Executive Summary

This vulnerability in Lychee allows authenticated users to upload small PDF files with artificially large page dimensions in the /MediaBox metadata. When processed, these files cause ImageMagick's Imagick::readImage() to consume excessive CPU resources before failing, leading to potential denial-of-service conditions. The issue stems from missing resource limits in ImageMagick's policy configuration.

Detection Guidance

Monitor CPU usage spikes during PDF uploads or processing. Check logs for ImagickHandler errors or timeouts. Use ImageMagick's policy.xml to set limits on PDF dimensions and resource consumption.

Impact Analysis

An attacker could upload a malicious PDF that occupies a web worker for extended periods in synchronous processing or clogs the shared image-processing queue in asynchronous Docker setups. This causes system unresponsiveness, delays other tasks, and may lead to denial-of-service as CPU resources are exhausted during processing.

Compliance Impact

This vulnerability primarily causes resource exhaustion leading to denial-of-service conditions, which could impact availability of systems handling sensitive data. For GDPR, this may affect the right to timely access or rectification of personal data if systems become unresponsive. For HIPAA, it could disrupt access to protected health information during critical operations.

Mitigation Strategies

Upgrade to Lychee v7.7.0 or later. Apply ImageMagick policy.xml limits for PDF dimensions and CPU usage. Implement timeouts for media processing jobs. Reject oversized PDFs during upload with validation checks.

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