What is CVE-2021-20829?

CVE-2021-20829 is a medium-severity vulnerability in Weseek Growi, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-09-21.

How severe is CVE-2021-20829?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Weseek Growi

CVE-2021-20829

Cross-site scripting vulnerability due to the inadequate tag sanitization in GROWI versions v4.2.19 and earlier allows remote attackers to execute an arbitrary script on the web browser of the user who accesses a specially crafted page.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-09-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.008 (53.3th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 53.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Weseek Growi
Weseek, Inc. Growi — versions versions v4.2.19 and earlier

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

jvn.jp/en/vu/JVNVU94889258/index.html (Third Party Advisory)
weseek.co.jp/security/2021/09/17/vulnerability/growi-prevent-multiple-xss-addit… (Vendor Advisory)

Frequently asked questions

What is CVE-2021-20829?: CVE-2021-20829 is a medium-severity vulnerability in Weseek Growi, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-09-21.
How severe is CVE-2021-20829?: Medium severity. CVSS v3 base score is 6.1 out of 10.