CVE-2021-42756

Description

Multiple stack-based buffer overflow vulnerabilities [CWE-121] in the proxy daemon of FortiWeb 5.x all versions, 6.0.7 and below, 6.1.2 and below, 6.2.6 and below, 6.3.16 and below, 6.4 all versions may allow an unauthenticated remote attacker to achieve arbitrary code execution via specifically crafted HTTP requests.

Remediation

Solution:

  • Upgrade to FortiWeb 7.0.0 or above, Upgrade to FortiWeb 6.3.17 or above, Upgrade to FortiWeb 6.2.7 or above. Upgrade to FortiWeb 6.1.3 or above. Upgrade to FortiWeb 6.0.8 or above.

Categories

9.8
CVSS
Severity: Critical
CVSS 3.1 •
EPSS 82.16% Top 5%
Vendor Advisory fortiguard.com
Affected: Fortinet FortiWeb
Published at:
Updated at:

References

Frequently Asked Questions

What is the severity of CVE-2021-42756?
CVE-2021-42756 has been scored as a critical severity vulnerability.
How to fix CVE-2021-42756?
To fix CVE-2021-42756: Upgrade to FortiWeb 7.0.0 or above, Upgrade to FortiWeb 6.3.17 or above, Upgrade to FortiWeb 6.2.7 or above. Upgrade to FortiWeb 6.1.3 or above. Upgrade to FortiWeb 6.0.8 or above.
Is CVE-2021-42756 being actively exploited in the wild?
It is possible that CVE-2021-42756 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~82% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-42756?
CVE-2021-42756 affects Fortinet FortiWeb.
This platform uses data from the NIST NVD, MITRE CVE, MITRE CWE, First.org and CISA KEV but is not endorsed or certified by these entities. CVE is a registred trademark of the MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. CWE is a registred trademark of the MITRE Corporation and the authoritative source of CWE content is MITRE's CWE web site.
© 2025 Under My Watch. All Rights Reserved.