What is CVE-2021-42233?

CVE-2021-42233 is a medium-severity vulnerability in Simple Blog Project, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2022-05-23.

How severe is CVE-2021-42233?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Simple Blog Project

CVE-2021-42233

The Simple Blog plugin in Wondercms 3.4.1 is vulnerable to stored cross-site scripting (XSS) vulnerability. When any user opens a particular blog hosted on an attackers' site, XSS may occur.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2022-05-23 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.009 (57.4th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 57.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Simple Blog Project
Wondercms — versions 3.4.1

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

hackerone.com/reports/485748 (Exploit, Third Party Advisory)
hackerone.com/reports/647130 (Exploit, Third Party Advisory)
hackerone.com/reports/961046 (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-42233?: CVE-2021-42233 is a medium-severity vulnerability in Simple Blog Project, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2022-05-23.
How severe is CVE-2021-42233?: Medium severity. CVSS v3 base score is 5.4 out of 10.