Vulnerability · Published Aug 6, 2026 · Assigned by VulnCheck
CVE-2026-70630FFmpeg 3.0 < 9.0 Uninitialized Heap Memory Read in Screenpresso Decoder
Medium 5.5
In plain English
A medium-severity security flaw in FFmpeg from FFmpeg. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | ffmpeg | no fix listed | DEBIAN-CVE-2026-70630 |
| Debian:13 | ffmpeg | no fix listed | DEBIAN-CVE-2026-70630 |
| Debian:14 | ffmpeg | 7:9.0.2-1 | DEBIAN-CVE-2026-70630 |
| Ubuntu:26.10 | ffmpeg | no fix listed | UBUNTU-CVE-2026-70630 |
Affected products (as reported)
Weakness: CWE-908 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
References
- Pull Request issue-tracking
- Introducing Commit related
- Patch Commit patch
- FFmpeg 9.0 Backport Commit patch
- https://www.vulncheck.com/advisories/ffmpeg-uninitialized-heap-memory-read-in-screenpresso-decoder third-party-advisory