CVE-2026-65704 FFmpeg CVE debrief

Who should care

Users and organizations that utilize FFmpeg for media processing should be aware of this vulnerability and take steps to mitigate it. This includes updating to a patched version of FFmpeg and ensuring that input files are validated and sanitized. Security teams and vulnerability management teams should review the affected scope and severity with the vendor and plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Technical summary

The vulnerability exists in the TY demuxer's demux_audio() function, which decrements packet size without bounds checking. This produces a negative size value that is passed to memcpy() in shorten_decode_frame(), triggering out-of-bounds writes. The vulnerability can be exploited via a crafted ffconcat file processed with the -safe 0 flag. This issue affects FFmpeg through version 8.1.2. Users and organizations should update to a patched version and validate input files to mitigate this vulnerability. The CVE record was published on 2026-07-23T20:17:21.973Z and last modified on 2026-07-27T20:34:24.887Z. The NVD entry is currently Awaiting Analysis. Defenders should verify the affected scope and severity with the vendor and plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Defensive priority

High

Recommended defensive actions

• Update FFmpeg to a patched version
• Validate and sanitize input files
• Monitor for suspicious activity
• Implement compensating controls
• Exception tracking and retest
• Review relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record was published on 2026-07-23T20:17:21.973Z and last modified on 2026-07-27T20:34:24.887Z. The NVD entry is currently Awaiting Analysis. There is limited information available about the vulnerability, and defenders should verify the affected scope and severity with the vendor. The TY demuxer's demux_audio() function decrements packet size without bounds checking, producing a negative size value that is passed to memcpy() in shorten_decode_frame(), where conversion to size_t wraps the value to near SIZE_MAX and triggers reads beyond the source allocation and writes far beyond the Shorten decoder's bitstream buffer. The vulnerability can be exploited by supplying a crafted ffconcat file processed with the -safe 0 flag.

Official resources