Vulnerability · Published Aug 6, 2026 · Assigned by VulnCheck
CVE-2026-70631FFmpeg 0.5 < 9.0 Uninitialized Heap Memory Read in TIFF 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 0.5 up to, but not including, 9.0 contain an uninitialized heap memory disclosure vulnerability in the native TIFF decoder in libavcodec/tiff.c. An attacker who can cause FFmpeg to decode a crafted TIFF file can supply a valid Deflate-compressed strip that terminates successfully after producing fewer bytes than the declared strip requires. The tiff_unpack_zlib() function allocates a heap buffer sized for the full declared strip but copies all declared rows via memcpy() regardless of how many bytes zlib actually decompressed, causing unwritten bytes that can contain stale data from prior heap allocations to be incorporated into decoded image output and potentially exposing sensitive data in persistent services.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | ffmpeg | no fix listed | DEBIAN-CVE-2026-70631 |
| Debian:13 | ffmpeg | no fix listed | DEBIAN-CVE-2026-70631 |
| Debian:14 | ffmpeg | 7:9.0.2-1 | DEBIAN-CVE-2026-70631 |
| Ubuntu:26.10 | ffmpeg | no fix listed | UBUNTU-CVE-2026-70631 |
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-tiff-decoder third-party-advisory