CVE-2026-70630 Details

A vulnerability has been identified in the FFmpeg multimedia framework, specifically in versions 3.0 prior to 9.0. The issue resides within the native Screenpresso decoder, located in 'libavcodec/screenpresso.c'. This vulnerability involves an uninitialized heap memory read, which can be exploited by attackers to retrieve sensitive memory contents. The exploitation occurs by sending a crafted SPV1 packet containing a valid zlib stream that decompresses to fewer bytes than required for the full frame. As a result, the 'screenpresso_decode_frame()' function fails to properly validate the decompressed byte count before copying the entire frame from the persistent 'ctx->inflated_buf' buffer. This oversight allows unwritten heap memory from previous allocations or frames to be included in the decoded output, potentially exposing sensitive information such as userspace addresses from ongoing decoding services.

Users can upgrade to FFmpeg version 9.0 or later, where this vulnerability has been fixed.