CVE-2024-7721: 'MemFray' - The Stack Overflow That Broke the 'Secure' Gateway

Vulnerability ID: CVE-2024-7721

CVSS Score: 9.8

Published: 2025-12-30

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'.

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.

⚠️ Exploit Status: ACTIVE

Technical Details

• 
  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)

Affected Systems

• Fortress Secure Gateway SG-1000


• Fortress Secure Gateway SG-5000


• Fortress Virtual Appliance v4.0 - v4.2


• 
  Fortress OS: >= 4.0.0, < 4.2.1 (Fixed in: 4.2.1)

Code Analysis

Commit: 7a3b19c

Fix buffer overflow in fast_parse header logic

@@ -45,6 +45,8 @@ while (*ptr) {

+ if (len >= MAX_HDR_LEN) return ERR_TOO_LONG;

  buf[len++] = *ptr++;

Exploit Details

• 
  ExploitDB: Fortress Gateway unauthenticated RCE python script


• 
  GitHub: Full ROP chain generator for Fortress OS 4.1

Mitigation Strategies

• Isolate the management interface immediately.


• Disable the 'FastParse' optimization feature via config if patching is impossible (performance penalty expected).


• Deploy WAF rules to drop HTTP headers exceeding 256 bytes.

Remediation Steps:

1. Login to the Fortress Admin Console.


2. Navigate to System > Firmware.


3. Download and apply Patch Release 4.2.1-hotfix.


4. Reboot the appliance.

References

• NVD Detail


• Disassembling Fortress: A Technical Deep Dive

Read the full report for CVE-2024-7721 on our website for more details including interactive diagrams and full exploit analysis.