CVE-2026-70630

Medium

Description

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.

SeverityMedium
CVSS5.5
Exploit probability—
ProductFfmpeg
PublishedAug 6, 2026
First seenAug 6, 2026
Weakness typeCWE-908CWE-908

How to fix

Affected products

ProductAffected versionsFixed in
ffmpeg ffmpeg3.0 ≤ v < 99

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