CVE-2026-121942 Details

A heap out-of-bounds read vulnerability has been identified in ZBar versions through 0.23.95. The issue resides in the SQ code decoder within the function '_zbar_sq_decode()' in 'zbar/sqcode.c'. This vulnerability allows attackers to read heap memory outside the allocated image buffer by crafting specific SQ code images. The exploitation involves sending an image with a distorted SQ code finder pattern near the edge, which creates unchecked sample coordinates. This not only crashes the decoder but also leaks memory bytes into the output.

To address this vulnerability, ZBar maintainers should clamp the sampling coordinates in the SQ code decoder to ensure they remain within the valid image boundaries. This can be done by checking and adjusting the coordinates before accessing the image data. Additionally, implementing a helper function to encapsulate the bounds checking for pixel sampling could enhance the overall robustness of the decoder.