CVE-2024-55591: Fortinet FortiOS and FortiProxy Authentication Bypass Vulnerability

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run Fortinet FortiOS and FortiProxy. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2025-01-14, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2025-01-21; treat that as the outer limit, not the target. CISA also lists it as known to be used in ransomware campaigns.
• EPSS 94.3%, percentile 99.9: FIRST’s model estimates a 94.3% chance of exploitation activity in the next 30 days, higher than 99.9% of all scored CVEs (very high). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Editorial verdict: Check exposure. FortiOS 7.0 Websocket Auth Bypass to Super-Admin — Exploited as a zero-day in late 2024 and patched in January 2025; anyone whose FortiOS 7.0 admin interface was internet-facing back then should audit admin and VPN accounts, not just the firmware version.

What it is

An Authentication Bypass Using an Alternate Path or Channel vulnerability [CWE-288] affecting FortiOS version 7.0.0 through 7.0.16 and FortiProxy version 7.0.0 through 7.0.19 and 7.2.0 through 7.2.12 allows a remote attacker to gain super-admin privileges via crafted requests to Node.js websocket module.

CISA’s summary

Fortinet FortiOS and FortiProxy contain an authentication bypass vulnerability that may allow an unauthenticated, remote attacker to gain super-admin privileges via crafted requests to Node.js websocket module.

Weakness type: CWE-288.

Product: Fortinet FortiOS and FortiProxy · Assigned by: fortinet · Published: 2025-01-14

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2025-01-14; federal due date 2025-01-21. Known ransomware use: Known.
• CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
• CISA SSVC assessment: exploitation active, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 94.35% probability of exploitation activity in the next 30 days; percentile 99.9.

Timeline

• 2025-01-14 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2025-01-14 — CVE record published by fortinet
• 2025-01-14 — erroneo.us brief: FortiOS 7.0 Websocket Auth Bypass to Super-Admin
• 2025-01-21 — CISA remediation deadline for US federal agencies
• 2026-08-05 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. Listed in CISA KEV notes (fortiguard.fortinet.com) fortiguard.fortinet.com

Vulnerability records

1. CVE.org record CVE-2024-55591 cve.org
2. NVD entry CVE-2024-55591 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov

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