FFmpeg <9.0: Uninit Heap Read in libavcodec/screenpresso.c
CVE-2026-70630 Published on August 6, 2026
FFmpeg 3.0 < 9.0 Uninitialized Heap Memory Read in Screenpresso Decoder
FFmpeg versions from 3.0 up to, but not including, 9.0 contain an uninitialized heap memory read vulnerability in the native Screenpresso decoder (libavcodec/screenpresso.c) that allows attackers to recover sensitive memory contents by supplying a crafted SPV1 packet with a valid zlib stream that decompresses fewer bytes than the full frame requires. The screenpresso_decode_frame() function fails to validate the produced byte count before calling av_image_copy_plane() to copy the complete frame dimensions from the persistent ctx->inflated_buf buffer, causing unwritten heap memory from prior allocations or prior frames to be copied into decoded output and potentially exposing sensitive data such as userspace addresses from persistent decoding services.
Vulnerability Analysis
CVE-2026-70630 is exploitable 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-2026-70630
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Affected Versions
FFmpeg:- Version 3.0 and below 9.0 is affected.