XSS in Stormshield Network Security

CVE-2026-8474

A vulnerability was discovered on Stormshield Network Security  * 4.3.0 to 4.3.41,  * 4.8.0 to 4.8.15,  * 5.0.0 to 5.0.5 It is possible to execute a reflected XSS attack on the login API available on Stormshield SNS appliance by executing a script on the victim's machine. The risks include the theft of cookies or other sensitive data, as well as the modification of page behavior, for example, by redirecting the victim to malicious websites.

Vulnerability class: XSS (Cross-Site Scripting)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (20.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 20.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-8474: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-8474?
CVE-2026-8474 is a medium-severity vulnerability in Stormshield Network Security, classified under Cross-site Scripting. CVSS score: 5.3/10. Published 2026-06-01.
How severe is CVE-2026-8474?
Medium severity. CVSS v3 base score is 5.3 out of 10.