Quick answers
- Is CVE-2026-30754 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-30754 being exploited in the wild.
- How severe is CVE-2026-30754?
- High severity, with a CVSS score of 8.8, published 8 September 2026.
- Which products and versions are affected?
- Ffmpeg before 8.1.
- Is there a fix for CVE-2026-30754?
- A patch was published on 2025-10-30: Fix merged into master Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-30754 attacked?
- It is attacked with local access, in a software library.
- Am I affected by CVE-2026-30754?
- Check whether you run Ffmpeg at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is a buffer overflow in the nal_send function of libavformat/rtpenc_h264_hevc.c, where a negative size parameter (size=-3) is incorrectly passed to memcpy during RTP transmission of H.264/HEVC streams. The root cause is insufficient validation of size parameters before memory operations. An attacker can exploit this by crafting a malicious input file processed with FFmpeg's RTP output mode (e.g., "ffmpeg -c copy -f rtp rtp://127.0.0.1:1234 -i input"). The vulnerability requires local access to trigger and was detected using AddressSanitizer. A fix was merged upstream in PR #20746, adding proper space checks for nal_length_size in the ff_rtp_send_h264_hevc function.
Affected products
- FFmpeg FFmpeg before 8.1
Timeline
- 2026-09-08: disclosed
- 2025-10-24: other: Fix PR #20746 opened
- 2025-10-30: patched: Fix merged into master