How severe is CVE-2026-84390?

CVE-2026-84390 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-84390 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-84390?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-84390 published?

CVE-2026-84390 was published on 2026-09-11.

CVE-2026-84390

CVE-2026-84390 is a critical-severity vulnerability with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-540.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (42nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-540
Published: 2026-09-11
Last modified: 2026-09-11

Description

A inclusion of sensitive information in source code vulnerability in Fortinet FortiMonitorOnSight 7.2.4 through 7.2.7, FortiMonitorOnSight 7.2.0 through 7.2.2 may allow attacker to improper access control via <insert attack vector here>

Frequently asked questions

What is CVE-2026-84390?: A inclusion of sensitive information in source code vulnerability in Fortinet FortiMonitorOnSight 7.2.4 through 7.2.7, FortiMonitorOnSight 7.2.0 through 7.2.2 may allow attacker to improper access control via <insert attack vector here>
How severe is CVE-2026-84390?: CVE-2026-84390 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-84390 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (42nd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-84390?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-84390 published?: CVE-2026-84390 was published on 2026-09-11.

References

https://fortiguard.fortinet.com/psirt/FG-IR-26-170

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