How severe is CVE-2021-26102?

CVE-2021-26102 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-26102 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 16% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26102?

CVE-2021-26102 affects Fortinet Fortiwan. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-26102?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2021-26102 have an EU (EUVD) identifier?

Yes. CVE-2021-26102 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-12923.

When was CVE-2021-26102 published?

CVE-2021-26102 was published on 2024-12-19 and last updated on 2026-06-17.

CVE-2021-26102

CVE-2021-26102 is a critical-severity vulnerability in Fortinet Fortiwan with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 16% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-22.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 16% (97th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2021-12923
Weakness: CWE-22
Affected product: Fortinet Fortiwan
Published: 2024-12-19
Last modified: 2026-06-17

Description

A relative path traversal vulnerability (CWE-23) in FortiWAN version 4.5.7 and below, 4.4 all versions may allow a remote non-authenticated attacker to delete files on the system by sending a crafted POST request. In particular, deleting specific configuration files will reset the Admin password to its default value.

Frequently asked questions

What is CVE-2021-26102?: A relative path traversal vulnerability (CWE-23) in FortiWAN version 4.5.7 and below, 4.4 all versions may allow a remote non-authenticated attacker to delete files on the system by sending a crafted POST request. In particular, deleting specific configuration files will reset the Admin password to its default value.
How severe is CVE-2021-26102?: CVE-2021-26102 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-26102 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 16% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26102?: CVE-2021-26102 affects Fortinet Fortiwan. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-26102?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2021-26102 have an EU (EUVD) identifier?: Yes. CVE-2021-26102 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-12923.
When was CVE-2021-26102 published?: CVE-2021-26102 was published on 2024-12-19 and last updated on 2026-06-17.

References

https://fortiguard.fortinet.com/psirt/FG-IR-21-048

Affected products (1)

cpe:2.3:a:fortinet:fortiwan:*:*:*:*:*:*:*:*

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