Critical

Critical FortiMail zero-day exploited in the wild (CVE-2026-104286)

Help Net Security

October 2, 2026 at 8:50 AM

Actively Exploited

CVE Zero-day Fortinet Exploit Vulnerability Critical

Overview

Fortinet has issued a warning to its customers regarding a zero-day vulnerability (CVE-2026-104286) in its FortiMail email security gateway. This flaw, which involves improper path traversal and handling of null bytes, allows unauthenticated attackers to exploit the system. Reports indicate that this vulnerability is currently being actively exploited in the wild, raising concerns about potential unauthorized access to sensitive email communications. Fortinet has advised users to implement a temporary workaround until a permanent fix is available. This vulnerability poses significant risks to organizations relying on FortiMail for email security, making it crucial for users to take immediate action to safeguard their systems.

Key Takeaways

Active Exploitation: This vulnerability is being actively exploited by attackers. Immediate action is recommended.
Affected Systems: FortiMail email security gateway
Action Required: Fortinet urges customers to apply the workaround provided until a fix is released.
Timeline: Newly disclosed

Original Article Summary

Fortinet is warning customers that attackers are exploiting a zero-day vulnerability (CVE-2026-104286) in FortiMail, its email security gateway. Fortinet says the flaw has been reported to be exploited in the wild, and urges customers to apply the workaround it shared until fixes are available. About CVE-2026-104286 “An Improper Limitation of a Pathname to a Restricted Directory (‘Path Traversal’) [CWE-22] and Improper Neutralization of NULL Byte or NULL Character [CWE-158] vulnerability may allow an unauthenticated attacker … More → The post Critical FortiMail zero-day exploited in the wild (CVE-2026-104286) appeared first on Help Net Security.

Impact

FortiMail email security gateway

Exploitation Status

This vulnerability is confirmed to be actively exploited by attackers in real-world attacks. Organizations should prioritize patching or implementing workarounds immediately.

Timeline

Newly disclosed

Remediation

Fortinet urges customers to apply the workaround provided until a fix is released. Specific details of the workaround have not been disclosed in the article.

Additional Information

This threat intelligence is aggregated from trusted cybersecurity sources. For the most up-to-date information, technical details, and official vendor guidance, please refer to the original article linked below.

Related Topics: This incident relates to CVE, Zero-day, Fortinet, and 3 more.

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