What is CVE-2026-24858?
An Authentication Bypass Using an Alternate Path or Channel vulnerability [CWE-288] vulnerability in Fortinet FortiAnalyzer 7.6.0 through 7.6.5, FortiAnalyzer 7.4.0 through 7.4.9, FortiAnalyzer 7.2.0 through 7.2.11, FortiAnalyzer 7.0.0 through 7.0.15, FortiManager 7.6.0 through 7.6.5, FortiManager 7.4.0 through 7.4.9, FortiManager 7.2.0 through 7.2.11, FortiManager 7.0.0 through 7.0.15, FortiOS 7.6.0 through 7.6.5, FortiOS 7.4.0 through 7.4.10, FortiOS 7.2.0 through 7.2.12, FortiOS 7.0.0 through 7.0.18, FortiProxy 7.6.0 through 7.6.4, FortiProxy 7.4.0 through 7.4.12, FortiProxy 7.2.0 through 7.2.15, FortiProxy 7.0.0 through 7.0.22, FortiWeb 8.0.0 through 8.0.3, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4.0 through 7.4.11 may allow an attacker with a FortiCloud account and a registered device to log into other devices registered to other accounts, if FortiCloud SSO authentication is enabled on those devices.
The record classifies CVE-2026-24858 under weakness class CWE-288. 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. 5 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 274 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)
- 85.7% probability of exploitation in the next 30 days, higher than 99.7% of all scored CVEs
- CISA KEV
- Listed since 2026-01-27, federal remediation deadline 2026-01-30
- Threadlinqs priority
- 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
- Published
- 2026-01-27, last modified 2026-06-09
Is CVE-2026-24858 being exploited?
CISA added CVE-2026-24858 to the Known Exploited Vulnerabilities catalog on 2026-01-27, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-01-30 under BOD 22-01. Weaponised exploit code for CVE-2026-24858 is publicly available. 5 public proof-of-concept repositories are tracked for this identifier. It currently carries a trending score of 53 in the Threadlinqs vulnerability feed.
- absholi7ly/CVE-2026-24858-FortiCloud-SSO-Authentication-Bypass (github)
- gagaltotal/cve-2026-24858 (github)
- m0d0ri205/CVE-2026-24858 (github)
- SimoesCTT/-CTT-NSP-Convergent-Time-Theory---Network-Stack-Projection-CVE-2026-24858- (github)
- SimoesCTT/SCTT-2026-33-0004-FortiCloud-SSO-Identity-Singularity (github)
Affected products and versions
- Fortinet: Fortianalyzer, Fortimanager, Fortiproxy, Fortiweb, Fortios
How to fix CVE-2026-24858
Vendor advisory: https://fortiguard.fortinet.com/psirt/FG-IR-26-060. Because CVE-2026-24858 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-01-30. 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-2026-24858
7 tracked threats in the Threadlinqs corpus reference CVE-2026-24858, either in the campaign’s CVE list or as an indicator on the campaign record.
- Rapid7 Q3 2026 Threat Landscape: High-Severity Flaws Exploited in 3 Days as The Gentlemen and Qilin Ransomware Dominate — HIGH · 2026-10-21
- FortiBleed: Ongoing Credential-Harvesting Campaign Against Fortinet FortiGate Firewalls and SSL VPN Gateways Feeds INC/Lynx and Payload Ransomware Access (FBI/USSS Alert) — HIGH · 2026-10-06
- Edge Infrastructure Under Siege: Tenable and SentinelOne Datasets Reveal Convergent Nation-State and Criminal Exploitation of Perimeter Devices — HIGH · 2026-08-26
- FortiBleed: Mass Credential Compromise Campaign Against Internet-Exposed Fortinet FortiGate Devices (86,644 Devices, 194 Countries) — CRITICAL · 2026-07-11
- FortiBleed Credential Theft Campaign Linked to INC and Lynx Ransomware Operations — CRITICAL · 2026-07-05
- FortiGate SSO Authentication Bypass Campaign (CVE-2025-59718, CVE-2025-59719, CVE-2026-24858) — CRITICAL · 2026-03-10
- Fortinet FortiCloud SSO Cross-Tenant Authentication Bypass (CVE-2026-24858) — CRITICAL · 2026-01-27
Sources
Enriched from CVE.org, FIRST EPSS, CISA KEV, public proof-of-concept repositories. Last verified by Threadlinqs on .