Skip to content

Fix VP8X reserved bytes use Position += 3 instead of Write, causing 3-byte truncation in alpha WebP images #3036

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
brianpopow merged 2 commits into from
Dec 28, 2025
+30 −1
Merged

Fix VP8X reserved bytes use Position += 3 instead of Write, causing 3-byte truncation in alpha WebP images #3036

Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
2edab61
Write into stream instead of simply just advancing it.
jrlost Dec 23, 2025
adf677a
Add test for writing reserved bytes in WebpVp8X
brianpopow Dec 28, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 4 additions & 1 deletion src/ImageSharp/Formats/Webp/Chunks/WebpVp8X.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -123,7 +123,10 @@ public void WriteTo(Stream stream)
long pos = RiffHelper.BeginWriteChunk(stream, (uint)WebpChunkType.Vp8X);

stream.WriteByte(flags);
stream.Position += 3; // Reserved bytes

Span<byte> reserved = stackalloc byte[3];
stream.Write(reserved);

WebpChunkParsingUtils.WriteUInt24LittleEndian(stream, this.Width - 1);
WebpChunkParsingUtils.WriteUInt24LittleEndian(stream, this.Height - 1);

Expand Down
Loading