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VulnerabilityCVE-2025-31366Published 2025-10-14

CVE-2025-31366 — Fortinet FortiSASE

mediumPublic exploit1 PoC repo

As of 2026-09-13, CVE-2025-31366 is a MEDIUM-severity vulnerability in Fortinet FortiSASE, CVSS v3.1 4.5, EPSS 0.4% (32.2th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2025-31366, most recently “Multiple Vulnerabilities in Fortigate NGFW on RUGGEDCOM APE1808 Devices (SSA-864900) — Including Actively Exploited FortiCloud SSO Bypass (CVE-2025-59718/-59719) and FortiOS Heap Overflow (CVE-2025-25249)”.

CVSS v3.1
4.5/10Medium
EPSS
0.4%Higher than 32.2% of scored CVEs
CISA KEV
NoNot in the KEV catalog
Tracked threats
1Campaigns referencing it
Priority
5.5/10Threadlinqs triage score
Published
Updated 2026-08-11
CVSS v3.1 4.5 (MEDIUM) · EPSS 0.4% (higher than 32.2% of all scored CVEs) · Priority 5.5/10 · Published 2025-10-14

Last updated:

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.

The record classifies CVE-2025-31366 under weakness class CWE-79. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first. 3 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 388 days ago.

Severity and exploitation probability

CVSS v3.1 base score
4.5 — MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N/E:P/RL:O/RC:C
EPSS (FIRST)
0.4% probability of exploitation in the next 30 days, higher than 32.2% of all scored CVEs
CISA KEV
Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority
5.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published
2025-10-14, last modified 2026-08-11

Is CVE-2025-31366 being exploited?

Weaponised exploit code for CVE-2025-31366 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 21 in the Threadlinqs vulnerability feed.

Affected products and versions

  • Fortinet: FortiSASE, FortiOS, FortiProxy

How to fix CVE-2025-31366

No vendor patch reference has been recorded for CVE-2025-31366 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

Threat activity tracking CVE-2025-31366

1 tracked threat in the Threadlinqs corpus references CVE-2025-31366, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on .

Other references