What’s Vulnerable › Vulnerabilities

CVE-2026-70630: FFmpeg 3.0 < 9.0 Uninitialized Heap Memory Read in Screenpresso Decoder

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-06 · updated 2026-09-01
• Weakness: CWE-908

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.

Affected products

• FFmpeg: from 3.0 before 9 — fixed in 9

How to fix

Upgrade to a fixed version: FFmpeg 9. Check the vendor advisory for mitigations.

References

• https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/705890061467ad550ecc1dad5eea07f28ccfb43e
• https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/9a3202a98b2e095b54dd784c3e01a09a676fc3fa
• https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/c22667d0fd7916a33fd3e79685b7246fc48f1a62
• https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23896
• https://www.vulncheck.com/advisories/ffmpeg-uninitialized-heap-memory-read-in-screenpresso-decoder

Get alerted when CVE-2026-70630 or the next vulnerability affects your stack