Public proof of conceptFix available

CVE-2021-26102

Q: Is CVE-2021-26102 actively exploited?

Active exploitation of CVE-2021-26102 has not been confirmed. Its EPSS score was 19.7% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-26102?

CVE-2021-26102 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.

A public proof of concept exists; no exploitation attested.

Published2024-12-19
Fixed in4.5.8
WeaknessCWE-22 · CWE-305

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2024-12-1914:15CVE publishedNVD
2026-10-2319:23First public proof of conceptPoC-in-GitHub
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-26102?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-26102?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Fortinet fortiwan

Branch	Affected	Fixed in	Source
4.x	≥ 4.4.0, < 4.5.8	4.5.8	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Fortinet fortiwan to 4.5.8

Advisories and patches

fortiguard.fortinet.comVendor Advisory

Detection

read 2026-10-23 19:23 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 1 repository, unverifiedSleepyCofe/CVE-2021-26102

Sources

CISA-ADPSSVC decisionnone2024-12-19
OpenCVESSVC decisionnone—
CNACVSS 3.19.8read 2026-10-23
NVDCVSS 3.19.1read 2026-10-23
CNAweakness (CWE)CWE-305read 2026-10-23
NVDweakness (CWE)CWE-22read 2026-10-23
FIRST EPSSEPSS score19.7 %read 2026-10-23
PoC-in-GitHubproof of concept1read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Published: 2024-12-19
Last Modified: 2026-06-17
NVD status: Analyzed

Frequently asked questions

What is CVE-2021-26102?

Is CVE-2021-26102 actively exploited?

Active exploitation of CVE-2021-26102 has not been confirmed. Its EPSS score was 19.7% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-26102?

CVE-2021-26102 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.

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