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NVD / CVE Program· CNA fortinet

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…

CriticalCVSS 9.1 · v3.1—Proof of concept No fix recorded

Noroxi assessment

Priority: Plan (action score 42/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 19.7% (FIRST EPSS); higher than 97.4% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • According to the record, no fixed version is available yet.

Add it to your regular patch cycle. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

Published
Dec 19, 2024
Updated
Jun 16, 2026
EPSS
19.7% · 97th percentile

Report tools

JSON

Action score

42

Plan

Add it to your regular patch cycle.

CVSS
36 / 40 · 9.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
6 / 30 · 19.7%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
9.1
CNA · fortinet
9.8
0.7 point gap

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:U/RC:C

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-26102

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
fortinetfortiwan

Versions reported by the vendor

Affected version ranges reported by the assigning authority (fortinet). Independent of NVD's CPE analysis and usually ahead of it.

  • Fortinet FortiWAN

    • 4.5.0 and later · up to and including 4.5.7affected · semver
    • 4.4.0 and later · up to and including 4.4.1affected · semver

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • fortinet fortiwan4.4.0 and later · before 4.5.8

Same product

fortinet: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-26112Multiple stack-based buffer overflow vulnerabilities [CWE-121] both in network daemons and in the command line interpreter of FortiWAN…
    40Plan
  • CVE-2021-26114Multiple improper neutralization of special elements used in an SQL command vulnerabilities in FortiWAN before 4.5.9 may allow an…
    39Monitor
  • CVE-2016-4965Fortinet FortiWan (formerly AscernLink) before 4.2.5 allows remote authenticated users with access to the nslookup functionality to execute…
    36Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2023-44251Dec 13, 2023 · ** UNSUPPORTED WHEN ASSIGNED **A improper limitation of a pathname to a restricted directory ('path traversal') vulnerability [CWE-22] in…
    35Monitor
  • ← EarlierCVE-2023-44252Dec 13, 2023 · ** UNSUPPORTED WHEN ASSIGNED **An improper authentication vulnerability [CWE-287] in Fortinet FortiWAN version 5.2.0 through 5.2.1 and…
    35Monitor
  • ← EarlierCVE-2021-26115Dec 19, 2024 · An OS command injection (CWE-78) vulnerability in FortiWAN version 4.5.7 and below Command Line Interface may allow a local, authenticated…
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:82021-12-09

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. First PoC-1106 d
  2. Published
  3. TodayNov 12, 2026+693 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2021-261150 days apartAn OS command injection (CWE-78) vulnerability in FortiWAN version 4.5.7 and below Command Line Interface may allow a local, authenticated…
    31Monitor

Not on record for this CVE: patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-305 · Authentication Bypass by Primary Weakness

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records