Threat Intelligence / CVE / CVE-2024-55591

CVE-2024-55591 — Fortinet Fortiproxy

CISA KEVRansomware

CVSS v3.1 9.8 (CRITICAL) · EPSS 94.1% (higher than 99.9% of all scored CVEs) · Priority 10/10 · Published 2025-01-14

As of 2025-10-24, CVE-2024-55591 is a CRITICAL-severity vulnerability in Fortinet Fortiproxy, CVSS v3.1 9.8, EPSS 94.1% (99.9th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-01-14), with a US federal remediation deadline of 2025-01-21, and CISA links it to known ransomware campaigns. Threadlinqs Intelligence links 7 tracked threat campaigns to CVE-2024-55591, most recently “The Gentlemen RaaS (GOLD SHERWOOD / hastalamuerte): FortiGate/VPN Intrusion Chain, GentleKiller BYOVD EDR Killers, and Rclone Exfiltration”.

Last updated: 2025-10-24

What is CVE-2024-55591?

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.

The record classifies CVE-2024-55591 under weakness classes CWE-288, NVD-CWE-Other. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 2 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 606 days ago.

Severity and exploitation probability

CVSS v3.1 base score: 9.8 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (FIRST): 94.1% probability of exploitation in the next 30 days, higher than 99.9% of all scored CVEs
CISA KEV: Listed since 2025-01-14, federal remediation deadline 2025-01-21 — used in known ransomware campaigns
Threadlinqs priority: 10/10 — CISA lists it as used in ransomware, which Threadlinqs scores at the maximum
Published: 2025-01-14, last modified 2025-10-24

Is CVE-2024-55591 being exploited?

CISA added CVE-2024-55591 to the Known Exploited Vulnerabilities catalog on 2025-01-14, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2025-01-21 under BOD 22-01. CISA flags the vulnerability as one used in known ransomware campaigns. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.

Affected products and versions

Fortinet: Fortiproxy, Fortios

How to fix CVE-2024-55591

Vendor advisory: https://fortiguard.fortinet.com/psirt/FG-IR-24-535. Because CVE-2024-55591 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2025-01-21. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2024-55591

7 tracked threats in the Threadlinqs corpus reference CVE-2024-55591, either in the campaign’s CVE list or as an indicator on the campaign record.

The Gentlemen RaaS (GOLD SHERWOOD / hastalamuerte): FortiGate/VPN Intrusion Chain, GentleKiller BYOVD EDR Killers, and Rclone Exfiltration — CRITICAL · 2026-09-01
The Gentlemen RaaS overtakes Qilin as #1 ransomware operation, wields GentleKiller EDR-killer framework (400+ processes, 8 BYOVD variants) and 90% affiliate payouts — HIGH · 2026-07-14
FortiBleed: Mass Credential Compromise Campaign Against Internet-Exposed Fortinet FortiGate Devices (86,644 Devices, 194 Countries) — CRITICAL · 2026-07-11
The Gentlemen Ransomware: Worm-Like Self-Propagation and Network-Wide Encryption via Storm-2697's RaaS Affiliate Program — CRITICAL · 2026-07-06
Q1 2026 Ransomware Landscape: Qilin Dominance, LockBit 5.0 Comeback, and FortiGate (CVE-2024-55591) / Oracle EBS (CVE-2025-61882) Mass Exploitation — CRITICAL · 2026-06-10
The Gentlemen Ransomware — FortiOS CVE-2024-55591 Authentication Bypass + Custom G-BOT C2 Framework — CRITICAL · 2026-06-05
LockBit 5.0 Cross-Platform Ransomware Analysis — CRITICAL · 2026-02-12

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2024-55591 are available via the Threadlinqs MCP server (Purple tier). View plans →

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