Security: Potential denial of service from unbounded image decoding#5266
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tomaioo wants to merge 1 commit intonextcloud:mainfrom
Open
Security: Potential denial of service from unbounded image decoding#5266tomaioo wants to merge 1 commit intonextcloud:mainfrom
tomaioo wants to merge 1 commit intonextcloud:mainfrom
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`resizeImage()` loads arbitrary image bytes into memory and decodes them without checking input size or dimensions first. If attacker-controlled or remote-fetched image data is very large or crafted, this may cause excessive memory/CPU consumption and degrade service availability. Signed-off-by: tomaioo <203048277+tomaioo@users.noreply.github.com>
hamza221
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Apr 23, 2026
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hamza221
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hamza221
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Hello,
I'm not sure if this is needed :
#5124 Whitelisted image formates were added in this PR #5124
And I think we can trust Instagram, Mastodon, Tumblr, Diaspora, Xing, Telegram, Gravatar Not send us Huge images
But even if we want to add the limit I would rather have a configurable limit than a hardcoded one
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Summary
Security: Potential denial of service from unbounded image decoding
Problem
Severity:
Medium| File:lib/Service/ImageResizer.php:L22resizeImage()loads arbitrary image bytes into memory and decodes them without checking input size or dimensions first. If attacker-controlled or remote-fetched image data is very large or crafted, this may cause excessive memory/CPU consumption and degrade service availability.Solution
Validate input size before decoding (e.g., maximum bytes), enforce pixel/dimension limits, and fail fast on oversized payloads. Prefer safe decoding paths with resource limits and consider rejecting unsupported/complex image formats.
Changes
lib/Service/ImageResizer.php(modified)