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CVE-2026-24640 is a stack-based buffer overflow vulnerability (CWE-121) residing in the API protection functionality of Fortinet FortiWeb. The flaw affects multiple versions, including 8.0.0 through 8.0.2, 7.6.0 through 7.6.6, all versions of 7.4 and 7.2, and versions 7.0.2 through 7.0.12 . The vulnerability allows a remote authenticated attacker to execute arbitrary code or commands on the underlying system. The attack is executed by sending specially crafted HTTP requests to the vulnerable appliance. The complexity of the attack is increased because the attacker must bypass two common memory protection mechanisms: stack protection and Address Space Layout Randomization (ASLR) . Despite these prerequisites, a successful exploit grants the attacker full control over the FortiWeb appliance with the privileges of the web server process. As of the publication date, no public exploit code is available, but the vendor has released security patches to address the issue .
dailycve form:
Platform: Fortinet FortiWeb
Version: 7.0.2-8.0.2
Vulnerability :Stack-based Overflow
Severity: High/Critical
date: 10 March 2026
Prediction: Patch Q2 2026
What Undercode Say:
Analytics:
The vulnerability exists due to insufficient bounds checking when processing HTTP request parameters. An attacker can send a payload that overflows a fixed-size stack buffer, overwriting the return address. By chaining this with an information leak to bypass ASLR and ROP techniques to bypass stack canaries, the attacker redirects execution flow to malicious shellcode.
Exploit:
Proof of Concept: Hypothetical buffer overflow trigger
This demonstrates a large string sent to a vulnerable parameter
TARGET="https://[FortiWeb-IP]:8443"
VULN_ENDPOINT="/api/v2/endpoint"
Create a large payload to overflow the buffer
PAYLOAD=$(python3 -c 'print("A" 5000)')
Send the crafted HTTP POST request
curl -k -X POST "$TARGET$VULN_ENDPOINT" \
-H "Content-Type: application/json" \
-d "{\"param\":\"$PAYLOAD\"}" \
--user "admin:password"
Protection from this CVE:
1. Update to patched version immediately execute update-now 2. If patching is delayed, restrict API access via Access List config system access-list edit 1 set name "block-api-exploit" config rule edit 1 set src-addr <trusted-IP-range> set service HTTPS next end next end 3. Enable strong input validation profiles for all web protection rules
Impact:
Successful exploitation leads to Remote Code Execution (RCE) on the FortiWeb appliance. An attacker can gain full administrative control, pivot to internal networks, disable security monitoring, and exfiltrate sensitive data processed by the WAF.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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