What is CVE-2021-26087?

CVE-2021-26087 is a medium-severity vulnerability in Fortinet Fortiwlc, classified under Cross-site Scripting. CVSS score: 4.3/10. Published 2025-03-17.

How severe is CVE-2021-26087?

Medium severity. CVSS v3 base score is 4.3 out of 10.

XSS in Fortinet Fortiwlc

CVE-2021-26087

An improper neutralization of input during web page generation in FortiWLC version 8.6.0, version 8.5.3 and below, version 8.4.8 and below, version 8.3.3 web interface may allow both authenticated remote attackers and non-authenticated attackers in the same network as the appliance to perform a stored cross site scripting attack (XSS) via injecting malicious payloads in different locations.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2025-03-17 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (24.3th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 24th percentile — 24.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000

Affected products

Fortinet Fortiwlc — versions 8.6.0, 8.5.0, 8.4.4

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

fortiguard.fortinet.com/psirt/FG-IR-20-137 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-26087?: CVE-2021-26087 is a medium-severity vulnerability in Fortinet Fortiwlc, classified under Cross-site Scripting. CVSS score: 4.3/10. Published 2025-03-17.
How severe is CVE-2021-26087?: Medium severity. CVSS v3 base score is 4.3 out of 10.