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 652 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 99.8% 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 2026-08-05
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. Weaponised exploit code for CVE-2024-55591 is publicly available. 11 public proof-of-concept repositories are tracked for this identifier. A ProjectDiscovery Nuclei detection template exists (http/cves/2024/CVE-2024-55591.yaml). It currently carries a trending score of 60 in the Threadlinqs vulnerability feed.
- watchtowrlabs/fortios-auth-bypass-poc-CVE-2024-55591 (github)
- watchtowrlabs/fortios-auth-bypass-check-CVE-2024-55591 (github)
- sysirq/fortios-auth-bypass-poc-CVE-2024-55591 (github)
- exfil0/CVE-2024-55591-POC (github)
- virus-or-not/CVE-2024-55591 (github)
- sysirq/fortios-auth-bypass-exploit-CVE-2024-55591 (github)
- UMChacker/CVE-2024-55591-POC (github)
- uLl0a/cve-2024-55591-poc (github)
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
17 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.
- Ransomware Surge in Q3 2026: The Gentlemen Overtakes Qilin as Rival Gangs Compete for Market Share — HIGH · 2026-10-24
- Rapid7 Q3 2026 Threat Landscape: High-Severity Flaws Exploited in 3 Days as The Gentlemen and Qilin Ransomware Dominate — HIGH · 2026-10-21
- Japan October 2026 Data Breach Surge: Web/API Compromises, Supplier Breaches, IDC Frontier Ransomware and AI-Assisted Probing (ARTEX) — HIGH · 2026-10-20
- Gentlemen Ransomware (Storm-2697): Double-Extortion RaaS with Fortinet Exploitation, BYOVD EDR Killers and GPO-Based Mass Deployment — HIGH · 2026-10-17
- Healthcare Sector Ransomware Targeting and Expanding Attack Surface (Qilin, Akira, DragonForce, LockBit, The Gentlemen) — HIGH · 2026-10-09
- Q3 2026 Record Ransomware Surge: 2,627 Claimed Attacks, Qilin and The Gentlemen Lead, Clop Resurgence via PTC Windchill CVE-2026-12569 — HIGH · 2026-10-09
- The Gentlemen RaaS: BYOVD AV/EDR Killing (ThrottleBlood.sys / CVE-2025-7771), FortiGate Initial Access and GPO/NETLOGON Ransomware Deployment — HIGH · 2026-10-08
- Qilin Ransomware Suspect Arrested in Japan, Extradited to Germany; Qilin Affiliate Exploited Check Point VPN Zero-Day CVE-2026-50751 — HIGH · 2026-10-07
- Rehub: Russian-Language Ransomware-as-a-Service Marketplace Absorbing RAMP's Displaced Operators — MEDIUM · 2026-09-16
- 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
- Seedworm (MuddyWater) Iranian MOIS APT Campaign Targeting U.S. Critical Infrastructure with Dindoor and Fakeset Backdoors — CRITICAL · 2026-03-06
- LockBit 5.0 Cross-Platform Ransomware Analysis — CRITICAL · 2026-02-12
Sources
Enriched from CVE.org, FIRST EPSS, CISA KEV, public proof-of-concept repositories, ProjectDiscovery Nuclei. Last verified by Threadlinqs on .