How severe is CVE-2021-42757?

CVE-2021-42757 has a CVSS 3.x base score of 6.7, rated medium severity. It is exploitable over local access with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-42757 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42757?

CVE-2021-42757 primarily affects Fortinet Fortiadc. In total, 19 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-42757?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-42757 published?

CVE-2021-42757 was published on 2021-12-08 and last updated on 2026-06-17.

CVE-2021-42757

CVE-2021-42757 is a medium-severity vulnerability in Fortinet Fortiadc with a CVSS 3.x base score of 6.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-120.

Key facts

Severity: Medium (CVSS 3.x base score 6.7)
CVSS v2: 4.6
EPSS exploit prediction: 0% (38th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Fortinet Fortiadc
Published: 2021-12-08
Last modified: 2026-06-17

Description

A buffer overflow [CWE-121] in the TFTP client library of FortiOS before 6.4.7 and FortiOS 7.0.0 through 7.0.2, may allow an authenticated local attacker to achieve arbitrary code execution via specially crafted command line arguments.

Frequently asked questions

What is CVE-2021-42757?: A buffer overflow [CWE-121] in the TFTP client library of FortiOS before 6.4.7 and FortiOS 7.0.0 through 7.0.2, may allow an authenticated local attacker to achieve arbitrary code execution via specially crafted command line arguments.
How severe is CVE-2021-42757?: CVE-2021-42757 has a CVSS 3.x base score of 6.7, rated medium severity. It is exploitable over local access with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-42757 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42757?: CVE-2021-42757 primarily affects Fortinet Fortiadc. In total, 19 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-42757?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-42757 published?: CVE-2021-42757 was published on 2021-12-08 and last updated on 2026-06-17.

References

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

Affected products (19)

cpe:2.3:a:fortinet:fortiadc:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortianalyzer:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortimail:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortimanager:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortindr:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortios-6k7k:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortios-6k7k:6.4.2:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortios-6k7k:6.4.6:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiportal:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiproxy:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiproxy:7.0.0:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiproxy:7.0.1:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortivoice:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:6.4.0:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:6.4.1:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortirecorder_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortiswitch:*:*:*:*:*:*:*:*

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