#VU70611 Input validation error in FFmpeg - CVE-2021-3566

Vulnerability identifier: #VU70611

Vulnerability risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-3566

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
FFmpeg
Universal components / Libraries / Libraries used by multiple products

Vendor: ffmpeg.sourceforge.net

Description

The vulnerability allows a remote attacker to manipulate data.

The vulnerability exists due to tty demuxer does not have a 'read_probe' function assigned to it. A remote attacker can create a legitimate "ffconcat" file that references an image, followed by a file the triggers the tty demuxer, the contents of the second file will be copied into the output file verbatim.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

FFmpeg: before 4.3

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External links
https://github.com/FFmpeg/FFmpeg/commit/3bce9e9b3ea35c54bacccc793d7da99ea5157532#diff-74f6b92a0541378ad15de9c29c0a2b0c69881ad9ffc71abe568b88b535e00a7f
https://lists.debian.org/debian-lts-announce/2021/08/msg00018.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.