What is CVE-2021-42756?

CVE-2021-42756 is a critical-severity vulnerability in Fortinet Fortiweb, classified under Stack-based Buffer Overflow. CVSS score: 9.3/10. Published 2023-02-16.

How severe is CVE-2021-42756?

Critical severity. CVSS v3 base score is 9.3 out of 10.

Is CVE-2021-42756 known to be exploited?

5 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in Fortinet Fortiweb

CVE-2021-42756

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 atta…

Vulnerability class: Buffer Overflow

EPSS: 0.665 (98.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:U/RC:C.

Affected products

Fortinet Fortiweb — versions 6.4.0, 6.3.0, 6.2.0

Weakness classification (CWE)

CWE-121 — Stack-based Buffer Overflow

Public proof-of-concept exploits

References

https://fortiguard.com/psirt/FG-IR-21-186

Frequently asked questions

What is CVE-2021-42756?: CVE-2021-42756 is a critical-severity vulnerability in Fortinet Fortiweb, classified under Stack-based Buffer Overflow. CVSS score: 9.3/10. Published 2023-02-16.
How severe is CVE-2021-42756?: Critical severity. CVSS v3 base score is 9.3 out of 10.
Is CVE-2021-42756 known to be exploited?: 5 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.