How severe is CVE-2021-24018?

CVE-2021-24018 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2021-24018 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-24018?

CVE-2021-24018 primarily affects Fortinet Fortios. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-24018?

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

When was CVE-2021-24018 published?

CVE-2021-24018 was published on 2021-08-04 and last updated on 2026-06-17.

CVE-2021-24018

CVE-2021-24018 is a medium-severity vulnerability in Fortinet Fortios with a CVSS 3.x base score of 4.3. 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-787.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
CVSS v2: 5.8
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Fortinet Fortios
Published: 2021-08-04
Last modified: 2026-06-17

Description

A buffer underwrite vulnerability in the firmware verification routine of FortiOS before 7.0.1 may allow an attacker located in the adjacent network to potentially execute arbitrary code via a specifically crafted firmware image.

Frequently asked questions

What is CVE-2021-24018?: A buffer underwrite vulnerability in the firmware verification routine of FortiOS before 7.0.1 may allow an attacker located in the adjacent network to potentially execute arbitrary code via a specifically crafted firmware image.
How severe is CVE-2021-24018?: CVE-2021-24018 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2021-24018 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-24018?: CVE-2021-24018 primarily affects Fortinet Fortios. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-24018?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-24018 published?: CVE-2021-24018 was published on 2021-08-04 and last updated on 2026-06-17.

References

https://fortiguard.com/advisory/FG-IR-21-046

Affected products (2)

cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:7.0.0:*:*:*:*:*:*:*

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