OpenEXR is the reference implementation and specification for the EXR image format, widely used in the motion picture industry. In versions before 3.2.11, 3.3.0 through 3.3.12, and 3.4.0 through 3.4.13, exrmultiview can write past a heap allocation when it combines two attacker-supplied, individually valid scanline EXR files whose union dataWindow is not aligned to one view's channel subsampling. The utility allocates sampled channel storage using a truncated union_width / xSampling, then reads the sampled input through a Slice based on the misaligned union window, producing a heap out-of-bounds write. The trigger is normal public-tool processing, such as exrmultiview left A.exr right B.exr out.exr with crafted but valid inputs, so this is not solely an API or caller-precondition issue. This issue is fixed in versions 3.2.11, 3.3.13, and 3.4.14.

A heap out-of-bounds write vulnerability exists in OpenEXR versions before 3.2.11, 3.3.0 through 3.3.12, and 3.4.0 through 3.4.13. The flaw resides in the exrmultiview utility, which can write past a heap allocation when combining two crafted but individually valid scanline EXR files whose union dataWindow is misaligned with one view's channel subsampling. The root cause is incorrect storage allocation using a truncated union_width divided by xSampling, followed by reading through a Slice based on the misaligned union window. The vulnerability can be triggered via normal command-line usage of the exrmultiview tool with attacker-supplied inputs, making it exploitable beyond just API misuse. The motion picture industry widely uses the EXR format, increasing the potential attack surface. Fixed versions are 3.2.11, 3.3.13, and 3.4.14. Multiple commits and a GitHub Security Advisory have been issued to address the issue.