How severe is CVE-2021-43064?

CVE-2021-43064 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-43064 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43064?

CVE-2021-43064 primarily affects Fortinet Fortiweb. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-43064?

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

When was CVE-2021-43064 published?

CVE-2021-43064 was published on 2021-12-08 and last updated on 2026-06-17.

CVE-2021-43064

CVE-2021-43064 is a medium-severity vulnerability in Fortinet Fortiweb 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-601.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
CVSS v2: 5.8
EPSS exploit prediction: 1% (45th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-601
Affected product: Fortinet Fortiweb
Published: 2021-12-08
Last modified: 2026-06-17

Description

A url redirection to untrusted site ('open redirect') in Fortinet FortiWeb version 6.4.1 and 6.4.0, version 6.3.15 and below, version 6.2.6 and below allows attacker to use the device as a proxy and reach external or protected hosts via redirection handlers.

Frequently asked questions

What is CVE-2021-43064?: A url redirection to untrusted site ('open redirect') in Fortinet FortiWeb version 6.4.1 and 6.4.0, version 6.3.15 and below, version 6.2.6 and below allows attacker to use the device as a proxy and reach external or protected hosts via redirection handlers.
How severe is CVE-2021-43064?: CVE-2021-43064 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-43064 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43064?: CVE-2021-43064 primarily affects Fortinet Fortiweb. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-43064?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-43064 published?: CVE-2021-43064 was published on 2021-12-08 and last updated on 2026-06-17.

References

https://fortiguard.com/advisory/FG-IR-21-168

Affected products (3)

cpe:2.3:a:fortinet:fortiweb:*:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:6.4.0:*:*:*:*:*:*:*
cpe:2.3:a:fortinet:fortiweb:6.4.1:*:*:*:*:*:*:*

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Other CWE-601 (Open Redirect) vulnerabilities

CVE-2018-3774 — Critical (CVSS 10.0): Incorrect parsing in url-parse <1.4.3 returns wrong hostname which leads to multiple vulnerabilities such as SSRF, Open…
CVE-2019-25282 — Critical (CVSS 9.8): V-SOL GPON/EPON OLT Platform v2.03 contains an open redirect vulnerability in the script that allows attackers to…
CVE-2020-36912 — Critical (CVSS 9.8): Plexus anblick Digital Signage Management 3.1.13 contains an open redirect vulnerability in the 'PantallaLogin' script…
CVE-2025-43526 — Critical (CVSS 9.8): This issue was addressed with improved URL validation. This issue is fixed in Safari 26.2, macOS Tahoe 26.2. On a Mac…
CVE-2025-55031 — Critical (CVSS 9.8): Malicious pages could use Firefox for iOS to pass FIDO: links to the OS and trigger the hybrid passkey transport. An…
CVE-2024-22891 — Critical (CVSS 9.8): Nteract v.0.28.0 was discovered to contain a remote code execution (RCE) vulnerability via the Markdown link.

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