The vulnerability exists in the tiff_unpack_zlib() function within libavcodec/tiff.c of FFmpeg versions >=0.5 and <9.0. When decoding a crafted TIFF file, the function allocates a heap buffer sized for the full declared strip but copies all declared rows regardless of the actual decompressed byte count. This results in uninitialized heap memory being copied into the output, potentially disclosing sensitive data from previous heap allocations.

An attacker able to provide a crafted TIFF file to the vulnerable FFmpeg decoder can cause disclosure of uninitialized heap memory. This may expose sensitive data residing in heap memory of the process using FFmpeg. The vulnerability does not affect integrity or availability, only confidentiality. Exploitation requires local or limited access to supply the crafted file and user interaction to trigger decoding.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Users should monitor vendor advisories for updates and avoid processing untrusted TIFF files with affected FFmpeg versions.