Package signatures

To ensure the integrity of the libjpeg-turbo binary packages, the RPM and DEB files and the source tarball are signed using the following key:
https://www.libjpeg-turbo.org/key/LJT-GPG-KEY
https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x0338c8d8d9fda62cf9c421bd7ec2dbb6f4dbf434
and the Windows installers are signed using a code signing certificate.

Packaging changes

• New builds of libjpeg-turbo-3.0.0-gcc.exe, libjpeg-turbo-3.0.0-gcc64.exe, libjpeg-turbo-3.0.0-vc.exe, and libjpeg-turbo-3.0.0-vc64.exe were uploaded on 2023-08-07. The new builds are now signed using a code signing certificate provided by the SignPath Foundation.

3.0.0

Significant changes relative to 3.0 beta2:

1. The TurboJPEG API now supports 4:4:1 (transposed 4:1:1) chrominance subsampling, which allows losslessly transposed or rotated 4:1:1 JPEG images to be losslessly cropped, partially decompressed, or decompressed to planar YUV images.

2. Fixed various segfaults and buffer overruns (CVE-2023-2804) that occurred when attempting to decompress various specially-crafted malformed 12-bit-per-component and 16-bit-per-component lossless JPEG images using color quantization or merged chroma upsampling/color conversion. The underlying cause of these issues was that the color quantization and merged chroma upsampling/color conversion algorithms were not designed with lossless decompression in mind. Since libjpeg-turbo explicitly does not support color conversion when compressing or decompressing lossless JPEG images, merged chroma upsampling/color conversion never should have been enabled for such images. Color quantization is a legacy feature that serves little or no purpose with lossless JPEG images, so it is also now disabled when decompressing such images. (As a result, djpeg can no longer decompress a lossless JPEG image into a GIF image.)

3. Fixed an oversight in 1.4 beta1[8] that caused various segfaults and buffer overruns when attempting to decompress various specially-crafted malformed 12-bit-per-component JPEG images using djpeg with both color quantization and RGB565 color conversion enabled.

4. Fixed an issue whereby jpeg_crop_scanline() sometimes miscalculated the downsampled width for components with 4x2 or 2x4 subsampling factors if decompression scaling was enabled. This caused the components to be upsampled incompletely, which caused the color converter to read from uninitialized memory. With 12-bit data precision, this caused a buffer overrun or underrun and subsequent segfault if the sample value read from uninitialized memory was outside of the valid sample range.

5. Fixed a long-standing issue whereby the tj3Transform() function, when used with the TJXOP_TRANSPOSE, TJXOP_TRANSVERSE, TJXOP_ROT90, or TJXOP_ROT270 transform operation and without automatic JPEG destination buffer (re)allocation or lossless cropping, computed the worst-case transformed JPEG image size based on the source image dimensions rather than the transformed image dimensions. If a calling program allocated the JPEG destination buffer based on the transformed image dimensions, as the API documentation instructs, and attempted to transform a specially-crafted 4:2:2, 4:4:0, 4:1:1, or 4:4:1 JPEG source image containing a large amount of metadata, the issue caused tj3Transform() to overflow the JPEG destination buffer rather than fail gracefully. The issue could be worked around by setting TJXOPT_COPYNONE. Note that, irrespective of this issue, tj3Transform() cannot reliably transform JPEG source images that contain a large amount of metadata unless automatic JPEG destination buffer (re)allocation is used or TJXOPT_COPYNONE is set.

6. Fixed a regression introduced by 3.0 beta2[6] that prevented the djpeg -map option from working when decompressing 12-bit-per-component lossy JPEG images.

7. Fixed an issue that caused the C Huffman encoder (which is not used by default on x86 and Arm CPUs) to read from uninitialized memory when attempting to transform a specially-crafted malformed arithmetic-coded JPEG source image into a baseline Huffman-coded JPEG destination image.