Is CVE-2020-12820 in the CISA KEV catalog?

No. CVE-2020-12820 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2020-12820?

CVE-2020-12820 has a CVSS v3 base score of 5.4 (MEDIUM).

What is the EPSS score for CVE-2020-12820?

CVE-2020-12820 has an EPSS score of 0.86% (54th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2020-12820?

Upgrade fortios to 6.0.11 or later.

CVE & CISA-KEV Catalog

CVE-2020-12820

MEDIUM

5.4

CVSS v3

NVD

Description

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.

CWE-121Stack-based Buffer Overflow CWE-787Out-of-bounds Write

How to fix

Remediation Available

fortiosNVD

Affected:>= 6.0.0, < 6.0.11Fixed in:6.0.11CVE-2020-12820derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityLow

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

Exploit Intelligence

0.86%probability of exploitation in 30 days

54thpercentile

Moderate risk: more likely to be exploited than 54% of all known CVEs.

References

Vendor Advisory1

fortiguard.fortinet.com

Related Vulnerabilities

Other CWE-121 (Stack-based Buffer Overflow) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-22457	Critical	9.0	100%	KEV + Ransom	Fix
CVE-2025-0282	Critical	9.0	100%	KEV + Ransom	-
CVE-2021-20038	Critical	9.8	100%	KEV + Ransom	-
CVE-2009-0927	High	8.8	97%	KEV	Fix
CVE-2020-10924	High	8.8	87%	-	-
CVE-2022-20705	Critical	10.0	80%	-	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-01-21.