CVE-2026-125233 · Package
NO FIX YET · SEE WHAT TO DO
FFmpeg's DVB subtitle encoder miscounts CLUT segment header size by two bytes, so a crafted file with many bitmap subtitle rectangles writes past its output buffer. An attacker who gets a file transcoded can corrupt heap memory, which may allow code execution.
first public Nov 9, 2026 · 1 source
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Systems that run FFmpeg to transcode video with DVB subtitle output, especially on untrusted uploaded media. Pipelines that never encode DVB subtitles or only process trusted files are less exposed. The sources do not list affected product ranges beyond 'through 9.0.2'.
Not affected if no-dvbsub-encoding, trusted-input-only
Who cares ffmpeg, libavcodec, media-processing
ffmpeg -version and compare against the fixed release in the product ranges (unknown in the sources).FFmpeg through 9.0.2 contains a heap buffer overflow vulnerability in dvbsub_encode() in libavcodec/dvbsubenc.c that undercounts each CLUT segment header by two bytes. Attackers can supply a file with many bitmap subtitle rectangles that, when transcoded to the dvbsub encoder, writes past the output buffer and corrupts heap memory.
This page as .md · .json · CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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