What is CVE-2021-20721?

CVE-2021-20721 is a critical-severity vulnerability in Kujirahand Konawiki, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2021-05-20.

How severe is CVE-2021-20721?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Arbitrary file upload in Kujirahand Konawiki

CVE-2021-20721

KonaWiki2 versions prior to 2.2.4 allows a remote attacker to upload arbitrary files via unspecified vectors. If the file contains PHP scripts, arbitrary code may be executed.

Vulnerability class: Unrestricted File Upload

Published 2021-05-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.015 (73.6th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 74th percentile — 73.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.015 · newest: 0.015 · change: 0.000

Affected products

Kujirahand Konawiki
Kujirahand Konawiki2 — versions versions prior to 2.2.4

Weakness classification (CWE)

CWE-434 — Unrestricted Upload of File with Dangerous Type

References

kujirahand.com/konawiki/ (Vendor Advisory)
jvn.jp/en/jp/JVN34232719/index.html (Third Party Advisory)

Frequently asked questions

What is CVE-2021-20721?: CVE-2021-20721 is a critical-severity vulnerability in Kujirahand Konawiki, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2021-05-20.
How severe is CVE-2021-20721?: Critical severity. CVSS v3 base score is 9.8 out of 10.