CVE-2021-26088

Name: CVE-2021-26088
Creator: NVD / NIST
Published: 2021-07-12T14:15:08.113+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.6/10EPSS 1.03%

Last modified Jun 17, 2026

CVE-2021-26088 is a critical-severity vulnerability rated 9.6/10 on the CVSS scale. An improper authentication vulnerability in FSSO Collector version 5.0.295 and below may allow an unauthenticated user to bypass a FSSO firewall policy and access the protected network via sending specifically crafted UDP login notification packets.. EPSS estimates a 1.03% chance of exploitation in the next 30 days.

Description

An improper authentication vulnerability in FSSO Collector version 5.0.295 and below may allow an unauthenticated user to bypass a FSSO firewall policy and access the protected network via sending specifically crafted UDP login notification packets.

Metrics

CVSS 3.1

9.6/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS Probability

1.03%

59.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-287

Affected Software

Vendor	Product	Versions
Fortinet	Fortinet Single Sign-On	< 6.4.6
Fortinet	Fortinet Single Sign-On	>= 7.0.0, < 7.0.1

References

https://fortiguard.com/advisory/FG-IR-20-191Vendor Advisory
https://fortiguard.com/advisory/FG-IR-20-191Vendor Advisory

Timeline

Published: Jul 12, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-26088?

How severe is CVE-2021-26088?

CVE-2021-26088 has a CVSS score of 9.6/10 (CRITICAL severity). The EPSS model estimates a 1.03% probability of exploitation in the next 30 days.

How do I fix CVE-2021-26088?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-26088?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST