CVE record · CVE-2021-42757

Buffer overflow in Fortinet FortiOS and others

CVSS 6.3 MediumEPSS 0.0052 · 44th percentile

Published by the CVE Program (CNA: fortinet) at 8 Dec 2021, 11:01 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
Fortinet	FortiOS	affected 7.0.0 to 7.0.2, inclusive semver affected 6.4.0 to 6.4.7, inclusive semver affected 6.2.0 to 6.2.9, inclusive semver affected 6.0.0 to 6.0.13, inclusive semver affected 5.6.0 to 5.6.14, inclusive semver affected 5.4.0 to 5.4.13, inclusive semver affected 5.2.0 to 5.2.15, inclusive semver affected 5.0.0 to 5.0.14, inclusive semver Other versions: unaffected
Fortinet	FortiDDoS-F	affected 6.4.0 to 6.4.1, inclusive semver affected 6.3.0 affected 6.2.0 to 6.2.2, inclusive semver affected 6.1.0 to 6.1.4, inclusive semver Other versions: unaffected
Fortinet	FortiVoice	affected 6.4.0 to 6.4.4, inclusive semver affected 6.0.0 to 6.0.10, inclusive semver Other versions: unaffected
Fortinet	FortiProxy	affected 7.0.0 to 7.0.1, inclusive semver affected 2.0.0 to 2.0.7, inclusive semver affected 1.2.0 to 1.2.13, inclusive semver affected 1.1.0 to 1.1.6, inclusive semver affected 1.0.0 to 1.0.7, inclusive semver Other versions: unaffected
Fortinet	FortiRecorder	affected 6.4.0 to 6.4.2, inclusive semver affected 6.0.0 to 6.0.10, inclusive semver affected 2.7.0 to 2.7.7, inclusive semver affected 2.6.0 to 2.6.3, inclusive semver Other versions: unaffected
Fortinet	FortiPortal	affected 6.0.0 to 6.0.10, inclusive semver affected 5.3.0 to 5.3.8, inclusive semver affected 5.2.0 to 5.2.6, inclusive semver affected 5.1.0 to 5.1.2, inclusive semver affected 5.0.0 to 5.0.3, inclusive semver Other versions: unaffected
Fortinet	FortiMail	affected 7.0.0 to 7.0.2, inclusive semver affected 6.4.0 to 6.4.6, inclusive semver affected 6.2.0 to 6.2.7, inclusive semver affected 6.0.0 to 6.0.12, inclusive semver affected 5.4.0 to 5.4.12, inclusive semver Other versions: unaffected
Fortinet	FortiAnalyzer	affected 7.0.0 to 7.0.2, inclusive semver affected 6.4.0 to 6.4.7, inclusive semver affected 6.2.0 to 6.2.13, inclusive semver affected 6.0.0 to 6.0.12, inclusive semver Other versions: unaffected
Fortinet	FortiNDR	affected 1.5.0 to 1.5.2, inclusive semver affected 1.4.0 affected 1.3.0 to 1.3.1, inclusive semver affected 1.2.0 affected 1.1.0 Other versions: unaffected
Fortinet	FortiDDoS	affected 5.5.0 to 5.5.1, inclusive semver affected 5.4.0 to 5.4.3, inclusive semver affected 5.3.0 to 5.3.2, inclusive semver affected 5.2.0 affected 5.1.0 affected 5.0.0 affected 4.7.0 affected 4.6.0 affected 4.5.0 affected 4.4.0 to 4.4.2, inclusive semver Other versions: unaffected
Fortinet	FortiSwitch	affected 7.0.0 to 7.0.3, inclusive semver affected 6.4.0 to 6.4.9, inclusive semver affected 6.2.0 to 6.2.7, inclusive semver affected 6.0.0 to 6.0.7, inclusive semver Other versions: unaffected
Fortinet	FortiADC	affected 6.2.0 to 6.2.2, inclusive semver affected 6.1.0 to 6.1.5, inclusive semver affected 6.0.0 to 6.0.4, inclusive semver affected 5.4.0 to 5.4.5, inclusive semver affected 5.3.0 to 5.3.7, inclusive semver affected 5.2.0 to 5.2.8, inclusive semver affected 5.1.0 to 5.1.7, inclusive semver affected 5.0.0 to 5.0.4, inclusive semver Other versions: unaffected
Fortinet	FortiWeb	affected 6.4.0 to 6.4.1, inclusive semver affected 6.3.0 to 6.3.16, inclusive semver affected 6.2.0 to 6.2.8, inclusive semver affected 6.1.0 to 6.1.4, inclusive semver affected 6.0.0 to 6.0.8, inclusive semver affected 5.9.0 to 5.9.2, inclusive semver affected 5.8.5 to 5.8.7, inclusive semver affected 5.8.0 to 5.8.3, inclusive semver affected 5.7.0 to 5.7.3, inclusive semver affected 5.6.0 to 5.6.2, inclusive semver affected 5.5.0 to 5.5.7, inclusive semver affected 5.4.0 to 5.4.1, inclusive semver and 4 more Other versions: unaffected
Fortinet	FortiManager	affected 7.0.0 to 7.0.2, inclusive semver affected 6.4.0 to 6.4.7, inclusive semver affected 6.2.0 to 6.2.13, inclusive semver affected 6.0.0 to 6.0.12, inclusive semver Other versions: unaffected

Identifiers: CVE-2021-42757
CNA: fortinet
Weakness (CWE): CWE-120
Tags: Fortinet FortiOS
Fortinet FortiDDoS-F
Fortinet FortiVoice
Fortinet FortiProxy
Fortinet FortiRecorder
Fortinet FortiPortal
Fortinet FortiMail
Fortinet FortiAnalyzer
Memory corruption
Published: 8 Dec 2021
Updated: 16 Oct 2025

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
6.3	Medium	3.1	CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:P/RL:U/RC:C	CNA (fortinet)

CISA KEV Not listed.
EPSS 0.0052, the 44th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 8 Dec 2021. New records show when each source confirmed them.

Sources

References from the CNA

fortiguard.com/advisory/FG-IR-21-173

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.