CVE-2026-65704: FFmpeg through 8.1.2 contains an out-of-bounds write vulnerability that allows attackers to cause heap corruption by supplying a crafted ffconcat file processed with the -safe 0 fl

highCVSS 7.8CVE-2026-65704

FFmpeg through 8.1.2 contains an out-of-bounds write vulnerability that allows attackers to cause heap corruption by supplying a crafted ffconcat file processed with the -safe 0 flag. 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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 7.8
Published: 2026-07-23
Last updated: 2026-07-27
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-65704

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-657040.13% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-65704	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

medium[NEW] [medium] ffmpeg: Multiple vulnerabilities allow code execution and DoScert-bund

Recent advisories for FFmpeg

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-67290: FreeRDP before 3.29.0 contains a heap out-of-bounds read vulnerability in the TSMF FFmpeg deco…nvd · 2026-08-01
high[UPDATE] [high] ffmpeg: Vulnerability allows code execution and Denial of Servicecert-bund · 2026-07-31
high[NEW] [high] ffmpeg: Multiple vulnerabilitiescert-bund · 2026-07-27
medium[UPDATE] [medium] ffmpeg: Vulnerability allows Denial of Servicecert-bund · 2026-07-27
highCVE-2026-66041: FFmpeg 7.0 through 8.1.2, fixed in commit 4da9812, contains a heap out-of-bounds write vulnera…nvd · 2026-07-24
highCVE-2026-66040: FFmpeg through 8.1.2, fixed in commit b506faf, contains a heap out-of-bounds write vulnerabili…nvd · 2026-07-24