How severe is CVE-2025-31366?

CVE-2025-31366 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2025-31366 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-31366?

CVE-2025-31366 primarily affects Fortinet Fortios. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-31366?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-31366 have an EU (EUVD) identifier?

Yes. CVE-2025-31366 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-34239.

When was CVE-2025-31366 published?

CVE-2025-31366 was published on 2025-10-14 and last updated on 2026-06-17.

CVE-2025-31366

CVE-2025-31366 is a medium-severity vulnerability in Fortinet Fortios with a CVSS 3.x base score of 4.7. 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-79.

Key facts

Severity: Medium (CVSS 3.x base score 4.7)
EPSS exploit prediction: 0% (29th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-34239
Weakness: CWE-79
Affected product: Fortinet Fortios
Published: 2025-10-14
Last modified: 2026-06-17

Description

An Improper Neutralization of Input During Web Page Generation vulnerability [CWE-79] vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2 all versions, FortiOS 7.0 all versions, FortiOS 6.4 all versions, FortiProxy 7.6.0 through 7.6.3, FortiProxy 7.4 all versions, FortiProxy 7.2 all versions, FortiProxy 7.0 all versions, FortiSASE 25.2.a may allow an unauthenticated attacker to perform a reflected cross site scripting (XSS) via crafted HTTP requests.

Frequently asked questions

What is CVE-2025-31366?: An Improper Neutralization of Input During Web Page Generation vulnerability [CWE-79] vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2 all versions, FortiOS 7.0 all versions, FortiOS 6.4 all versions, FortiProxy 7.6.0 through 7.6.3, FortiProxy 7.4 all versions, FortiProxy 7.2 all versions, FortiProxy 7.0 all versions, FortiSASE 25.2.a may allow an unauthenticated attacker to perform a reflected cross site scripting (XSS) via crafted HTTP requests.
How severe is CVE-2025-31366?: CVE-2025-31366 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2025-31366 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-31366?: CVE-2025-31366 primarily affects Fortinet Fortios. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-31366?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-31366 have an EU (EUVD) identifier?: Yes. CVE-2025-31366 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-34239.
When was CVE-2025-31366 published?: CVE-2025-31366 was published on 2025-10-14 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiproxy:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortisase:25.3.40:*:*:*:feature:*:*:*
cpe:2.3:a:fortinet:fortisase:25.3.40:*:*:*:mature:*:*:*

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