How severe is CVE-2021-43206?

CVE-2021-43206 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2021-43206 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-2021-43206?

CVE-2021-43206 primarily affects Fortinet Fortiproxy. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-43206?

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

When was CVE-2021-43206 published?

CVE-2021-43206 was published on 2022-05-04 and last updated on 2026-06-17.

CVE-2021-43206

CVE-2021-43206 is a medium-severity vulnerability in Fortinet Fortiproxy 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-209.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
CVSS v2: 4.3
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-209
Affected product: Fortinet Fortiproxy
Published: 2022-05-04
Last modified: 2026-06-17

Description

A server-generated error message containing sensitive information in Fortinet FortiOS 7.0.0 through 7.0.3, 6.4.0 through 6.4.8, 6.2.x, 6.0.x and FortiProxy 7.0.0 through 7.0.1, 2.0.x allows malicious webservers to retrieve a web proxy's client username and IP via same origin HTTP requests triggering proxy-generated HTTP status codes pages.

Frequently asked questions

What is CVE-2021-43206?: A server-generated error message containing sensitive information in Fortinet FortiOS 7.0.0 through 7.0.3, 6.4.0 through 6.4.8, 6.2.x, 6.0.x and FortiProxy 7.0.0 through 7.0.1, 2.0.x allows malicious webservers to retrieve a web proxy's client username and IP via same origin HTTP requests triggering proxy-generated HTTP status codes pages.
How severe is CVE-2021-43206?: CVE-2021-43206 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2021-43206 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-2021-43206?: CVE-2021-43206 primarily affects Fortinet Fortiproxy. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-43206?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-43206 published?: CVE-2021-43206 was published on 2022-05-04 and last updated on 2026-06-17.

References

https://fortiguard.com/psirt/FG-IR-21-231

Affected products (2)

cpe:2.3:a:fortinet:fortiproxy:*:*:*:*:*:*:*:*
cpe:2.3:o:fortinet:fortios:*:*:*:*:*:*:*:*

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