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CVE-2020-12820

MEDIUM · CVSS 5.4EPSS 0.9%EU EUVD

Under non-default configuration, a stack-based buffer overflow in FortiOS version 6.0.10 and below, version 5.6.12 and below may allow a remote attacker authenticated to the SSL VPN to crash the FortiClient NAC daemon (fcnacd) and potentially execute arbitrary code via requesting a large FortiClient file name. We are not aware of proof of concept code successfully achieving the latter.

Key facts

CVSS score
5.4 (v3.1)
Severity
MEDIUM
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
Weakness (CWE)
CWE-121
EPSS score
0.9% (58th percentile)
In CISA KEV
No
In EU EUVD
Yes (EUVD-2020-5103)
Published
December 19, 2024
NVD last modified
June 17, 2026
Status
Analyzed

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2020-5103 in the EU Vulnerability Database. Last updated in EUVD on December 20, 2024.

View on the EU Vulnerability Database

Affected products

  • fortinet / fortios

Certified products that may be affected

4 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.

  • FortiOS 5.6 - Fortinet, Inc. - FIPS 140 3639 - historical
  • FortiOS 5.2 - Fortinet, Inc. - FIPS 140 2765 - historical
  • FortiOS™ - Fortinet, Inc. - FIPS 140 1754 - historical
  • FortiOS - Fortinet, Inc. - FIPS 140 1431 - historical

References

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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