vulnerability / NVI-00011946 / Revision 1
Pillow: Heap buffer overflow in ImagingJpegDecode
GitHub lists this reviewed advisory for Pillow. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
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02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
Pillow
source listed<= 12.3.0
## Summary `JpegImageFile.draft()` — which `Image.thumbnail()` calls automatically — requests 1/2, 1/4 or 1/8 scaled JPEG output and shrinks `self._size` and the tile extents to match, so `_setimage()` allocates a single-row decode buffer of `ceil(W/s)` samples. `ImagingJpegDecode()` sets `cinfo.scale_num`/`scale_denom`, calls `jpeg_start_decompress()`, and then reads scanlines into that buffer without ever comparing `cinfo.output_width`, `cinfo.output_height` or `cinfo.out_color_components` against `state->xsize`, `state->ysize` and `state->bits`. libjpeg-turbo 3.x decodes lossless (SOF3) JPEG, but hardwires lossless streams to no scaling — the requested `scale_denom` is silently discarded. It therefore returns full-width `W`-sample rows into a buffer sized for `ceil(W/s)`. Each `jpeg_read_scanlines()` call writes `(W - ceil(W/s)) x components` bytes past the end of the heap allocation, and the overflowing bytes are the decoded pixel values, which are byte-exact for an 8-bit grayscale lossless image. The input is a standards-compliant JPEG, so `Image.open(..., formats=["JPEG"])` does not prevent it. Pillow's Python SOF parser already accepts marker `0xFFC3` ("SOF3", "Spatial lo
03 / Response
What to do next
- investigate
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04 / Limits
What this report cannot establish
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05 / Provenance
Sources you can inspect
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- GHSA-8g5g-8vmr-9782 ↗
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- Revision 1 ·
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