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Vulnerability details: VCID-z3nq-j291-a7a4
Vulnerability ID VCID-z3nq-j291-a7a4
Aliases CVE-2021-3566
Summary Prior to ffmpeg version 4.3, the tty demuxer did not have a 'read_probe' function assigned to it. By crafting 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 (as long as the `-vcodec copy` option is passed to ffmpeg).
Status Published
Exploitability 0.5
Weighted Severity 5.0
Risk 2.5
Affected and Fixed Packages Package Details
Weaknesses (0)
There are no known CWE.
System Score Found at
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
epss 0.00103 https://api.first.org/data/v1/epss?cve=CVE-2021-3566
cvssv3.1 4.4 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv2 4.3 https://nvd.nist.gov/vuln/detail/CVE-2021-3566
cvssv3.1 5.5 https://nvd.nist.gov/vuln/detail/CVE-2021-3566
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2021-3566
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-20891
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-20892
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-20896
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-21688
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-21697
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3566
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://github.com/FFmpeg/FFmpeg/commit/3bce9e9b3ea35c54bacccc793d7da99ea5157532#diff-74f6b92a0541378ad15de9c29c0a2b0c69881ad9ffc71abe568b88b535e00a7f
https://lists.debian.org/debian-lts-announce/2021/08/msg00018.html
cpe:2.3:a:ffmpeg:ffmpeg:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:ffmpeg:ffmpeg:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
CVE-2021-3566 https://nvd.nist.gov/vuln/detail/CVE-2021-3566
USN-USN-5167-1 https://usn.ubuntu.com/USN-5167-1/
No exploits are available.
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:N/A:N Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: AV:N/AC:M/Au:N/C:P/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-3566
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-3566
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.29098
EPSS Score 0.00103
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:42:43.083716+00:00 Ubuntu USN Importer Import https://usn.ubuntu.com/USN-5167-1/ 37.0.0