ImageSharp is a 2D graphics library. From 4.0.0 until 4.1.2, ExrBaseDecompressor.UndoZipCompression accepts a nonempty ZIP or ZIPS inflate result that is shorter than the EXR block's required size. ZipExrCompression.Decompress reconstructs the returned prefix while ExrDecoderCore processes the full expected block from a buffer obtained through Configuration.Default, allowing bytes retained from a completed prior ImageSharp operation to appear in decoded pixels. Applications that expose pixels or output from the later attacker-controlled EXR decode can disclose process-local image data. This issue is fixed in version 4.1.2.

Affected: NuGet: SixLabors.ImageSharp

## Summary

A crafted ZIP-compressed OpenEXR image can return stale memory from a prior ImageSharp operation as decoded pixels. The ZIP decoder accepts a non-empty inflate result shorter than the EXR block's required size, then the EXR decoder reads the full expected block.

This is a process-local, cross-operation information-disclosure defect. It is relevant when an application uses the shared `Configuration.Default` allocator for separate image operations and exposes pixels or output derived from a later attacker-controlled EXR decode. Whether that creates a network attack path depends on the host application.

No active exploitation is known.

## Affected package and versions

- Package: `SixLabors.ImageSharp` (NuGet) - Affected published releases: **4.0.0, 4.1.0, and 4.1.1** - Affected range: `>= 4.0.0, <= 4.1.1` - Commit `0815358f9202a78bc7f3b83e19282dc3654b500f` corresponds to release **v4.1.1**.

EXR support first appears in v4.0.0. The cross-operation PoC exposes the prior-operation marker on each published 4.x release, while the full-inflate control does not expose it on any of them. ## Details

For ZIP/ZIPS EXR compression, [`ExrDecoderCore`](https://github.com/SixLabors/ImageSharp/blob/0815358f9202a78bc7f3b83e19282dc3654b500f/src/ImageSharp/Formats/Exr/ExrDecoderCore.cs#L169-L205) allocates the expected block buffer without `AllocationOptions.Clean` and later interprets the complete buffer as channel data. [`ZipExrCompression`](https://github.com/SixLabors/ImageS…