CISA: Fortinet Releases Guidance to Address Ongoing Exploitation of Authentication Bypass Vulnerability CVE-2026-24858


Newly disclosed vulnerability Common Vulnerabilities and Exposures (CVE)-2026-24858 [Common Weakness Enumeration (CWE)-288: Authentication Bypass Using an Alternate Path or Channel] allows malicious actors with a FortiCloud account and a registered device to log in to separate devices registered to other users in FortiOS, FortiManager, FortiWeb, FortiProxy, and FortiAnalyzer, if FortiCloud single sign on (SSO) is enabled on devices.

Users are vulnerable to CVE-2026-24858 even if they updated Fortinet devices to address previously disclosed FortiCloud SSO bypass vulnerabilities CVE-2025-59718 and CVE-2025-59719 [CWE-347: Improper Verification of Cryptographic Signature]. CVE-2025-59718 and CVE-2025-59719 affect FortiOS, FortiWeb, FortiProxy, and FortiSwitch Manager, and allow malicious actors to bypass the SSO login authentication via a crafted Security Assertion Markup Language (SAML) message.

Read more…
Source: U.S. Cybersecurity and Infrastructure Security Agency


Sign up for the Cyber Security Review Newsletter
The latest cyber security news and insights delivered right to your inbox


Related:

  • APT Actors Exploiting Newly Identified Vulnerability in ManageEngine ADSelfService Plus

    September 16, 2021

    This joint advisory is the result of analytic efforts between the Federal Bureau of Investigation (FBI), United States Coast Guard Cyber Command (CGCYBER), and the Cybersecurity and Infrastructure Security Agency (CISA) to highlight the cyber threat associated with active exploitation of a newly identified vulnerability (CVE-2021-40539) in ManageEngine ADSelfService Plus—a self-service password management and single ...

  • Hacker-made Linux Cobalt Strike beacon used in ongoing attacks

    September 14, 2021

    An unofficial Cobalt Strike Beacon Linux version made by unknown threat actors from scratch has been spotted by security researchers while actively used in attacks targeting organizations worldwide. Cobalt Strike is a legitimate penetration testing tool designed as an attack framework for red teams (groups of security professionals who act as attackers on their own org’s ...

  • Pair of Google Chrome Zero-Day Bugs Actively Exploited

    September 14, 2021

    Google has addressed two zero-day security bugs that are being actively exploited in the wild. As part of the internet giant’s latest stable channel release (version 93.0.4577.82 for Windows, Mac and Linux), it fixed 11 total vulnerabilities, all of them rated high-severity. The two zero days are tracked as CVE-2021-30632 and CVE-2021-30633. “Google is aware that exploits ...

  • Apple rushes to block ‘zero-click’ iPhone spyware

    September 14, 2021

    Apple has issued a software patch to block so-called “zero-click” spyware that could infect iPhones and iPads. Independent researchers identified the flaw, which lets hackers access devices through the iMessage service even if users do not click on a link or file. The problem affects all of the technology giant’s operating systems, the researchers said. Read more… Source: BBC ...

  • Windows MSHTML zero-day exploits shared on hacking forums

    September 12, 2021

    Threat actors are sharing Windows MSHTML zero-day (CVE-2021-40444) tutorials and exploits on hacking forums, allowing other hackers to start exploiting the new vulnerability in their own attacks. Last Tuesday, Microsoft disclosed a new zero-day vulnerability in Windows MSHTML that allows threat actors to create malicious documents, including Office and RTF docs, to execute commands on a ...

  • Remote Code Execution 0-Day (CVE-2021-40444) Hits Windows, Triggered Via Office Docs

    September 9, 2021

    Microsoft has disclosed the existence of a new zero-day vulnerability that affects multiple versions of Windows. This vulnerability (designated as CVE-2021-40444) is currently delivered via malicious Office 365 documents and requires user input to open the file to trigger. It should be noted that by default, Office documents downloaded from the internet are opened either ...