CVE-2024-7721
9.892.45%
CVE-2024-7721: 'MemFray' - The Stack Overflow That Broke the 'Secure' Gateway
Alon Barad
Software EngineerJan 2, 2026·4 min read·7 visits
Active ExploitationCISA KEV Listed
Executive Summary (TL;DR)
The 'Fortress' Gateway loves speed so much it forgot how to count. By sending a specially crafted HTTP request with an oversized 'X-Custom-Auth' header, an attacker can overflow a stack buffer, overwrite the return address, and gain a root shell. No authentication required. CVSS 9.8. Patch immediately.
A critical stack-based buffer overflow in the core HTTP packet parser of the widely used 'Fortress' Secure Gateway appliance allows unauthenticated remote attackers to execute arbitrary code with root privileges. The vulnerability stems from an insecure implementation of a custom string copying routine designed for 'performance optimization'.
Fix Analysis (1)
Technical Appendix
CVSS Score
9.8/ 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HEPSS Probability
92.45%
Top 4% most exploited
45,000
Estimated exposed hosts via Shodan
Affected Systems
Fortress Secure Gateway SG-1000Fortress Secure Gateway SG-5000Fortress Virtual Appliance v4.0 - v4.2
Affected Versions Detail
| Product | Affected Versions | Fixed Version |
|---|---|---|
Fortress OS Fortress Networks | >= 4.0.0, < 4.2.1 | 4.2.1 |
| Attribute | Detail |
|---|---|
| CWE ID | CWE-121 (Stack-based Buffer Overflow) |
| CVSS v3.1 | 9.8 (Critical) |
| Vector | AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Attack Vector | Network (HTTP) |
| Exploit Status | Functional PoC Available |
| EPSS Score | 0.9245 (High Probability) |
MITRE ATT&CK Mapping
CWE-121
Stack-based Buffer Overflow
A stack-based buffer overflow condition exists when a program writes to a memory address on the program's call stack outside of the intended data structure.
Known Exploits & Detection
Vulnerability Timeline
Vulnerability discovered by internal red team
2024-04-20
Vendor notified
2024-05-01
Patch released (v4.2.1)
2024-05-10
Added to CISA KEV
2024-05-12
Public PoC released on Twitter
2024-05-13