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.

Published: 2025-03-17 Last update: 2025-07-24 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-26087 is rated Low Risk (24.6/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.29%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-26087

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.11% 0.29% +0.18%
2 2026-04-27 0.15% 0.11% -0.04%
3 2026-04-25 — 0.15% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-26087

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 1.4 [email protected]
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]

Weakness enumeration for CVE-2021-26087

Affected software / configurations for CVE-2021-26087

Vendor Product Version Raw CPE
fortinet fortiwlc >= 8.4.0, <= 8.4.2 cpe:2.3:a:fortinet:fortiwlc:*:*:*:*:*:*:*:*
fortinet fortiwlc >= 8.4.4, < 8.5.4 cpe:2.3:a:fortinet:fortiwlc:*:*:*:*:*:*:*:*
fortinet fortiwlc 8.3.3 cpe:2.3:a:fortinet:fortiwlc:8.3.3:*:*:*:*:*:*:*
fortinet fortiwlc 8.6.0 cpe:2.3:a:fortinet:fortiwlc:8.6.0:*:*:*:*:*:*:*

References for CVE-2021-26087

cvelogic Threat Intelligence