FFmpeg Uninitialized Heap Leak in TIFF Decoder (v0.5-9.0)
CVE-2026-70631 Published on August 6, 2026
FFmpeg 0.5 < 9.0 Uninitialized Heap Memory Read in TIFF Decoder
FFmpeg versions from 0.5 up to, but not including, 9.0 contain an uninitialized heap memory disclosure vulnerability in the native TIFF decoder in libavcodec/tiff.c. An attacker who can cause FFmpeg to decode a crafted TIFF file can supply a valid Deflate-compressed strip that terminates successfully after producing fewer bytes than the declared strip requires. The tiff_unpack_zlib() function allocates a heap buffer sized for the full declared strip but copies all declared rows via memcpy() regardless of how many bytes zlib actually decompressed, causing unwritten bytes that can contain stale data from prior heap allocations to be incorporated into decoded image output and potentially exposing sensitive data in persistent services.
Vulnerability Analysis
CVE-2026-70631 can be exploited with local system access. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
Use of Uninitialized Resource
The software uses or accesses a resource that has not been initialized. When a resource has not been properly initialized, the software may behave unexpectedly. This may lead to a crash or invalid memory access, but the consequences vary depending on the type of resource and how it is used within the software.
Products Associated with CVE-2026-70631
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Affected Versions
FFmpeg:- Version 0.5 and below 9.0 is affected.