Possible FortiGate RCE via Chunked hostcheck_validate Request (CVE-2024-21762)
- Category
- webserver
- Author
- HuntRule
- Published
- 2026-05-25
- Updated
- 2026-08-28
ATT&CK techniques
Initial AccessRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule detects POST requests to the FortiGate SSL VPN hostcheck_validate endpoint using Transfer-Encoding chunked, matching the out-of-bounds write exploited in CVE-2024-21762 as analyzed by Assetnote. The exploit relies on a malformed chunked body with a zero-length terminator and excess trailer lines to corrupt memory and reach code execution. Detecting chunked requests to this specific endpoint surfaces attempts against the vulnerable parser.
Reporting behind it
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