What is CVE-2026-40321?

CVE-2026-40321 is a high-severity vulnerability in Dnnsoftware Dnn.platform, classified under Improper Neutralization of Alternate XSS Syntax. CVSS score: 8.0/10. Published 2026-04-17.

How severe is CVE-2026-40321?

High severity. CVSS v3 base score is 8.0 out of 10.

XSS in Dnnsoftware Dnn.platform

CVE-2026-40321

DNN (formerly DotNetNuke) is an open-source web content management platform (CMS) in the Microsoft ecosystem. Prior to version 10.2.2, a user could upload a specially crafted SVG file that could include scripts that can target both authent…

EPSS: 0.076 (93.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H.

Affected products

Dnnsoftware Dnn.platform — versions < 10.2.2
Dnnsoftware Dotnetnuke

Weakness classification (CWE)

CWE-87 — Improper Neutralization of Alternate XSS Syntax

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
security-advisories@github.com (x_refsource_MISC, Release Notes)

Frequently asked questions

What is CVE-2026-40321?: CVE-2026-40321 is a high-severity vulnerability in Dnnsoftware Dnn.platform, classified under Improper Neutralization of Alternate XSS Syntax. CVSS score: 8.0/10. Published 2026-04-17.
How severe is CVE-2026-40321?: High severity. CVSS v3 base score is 8.0 out of 10.