How severe is CVE-2020-3400?

CVE-2020-3400 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-3400 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-3400?

CVE-2020-3400 primarily affects Cisco Ios Xe. In total, 15 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-3400?

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

When was CVE-2020-3400 published?

CVE-2020-3400 was published on 2020-09-24 and last updated on 2026-06-17.

CVE-2020-3400

CVE-2020-3400 is a high-severity vulnerability in Cisco Ios Xe with a CVSS 3.x base score of 8.8. 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-862.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.5
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-862
Affected product: Cisco Ios Xe
Published: 2020-09-24
Last modified: 2026-06-17

Description

A vulnerability in the web UI feature of Cisco IOS XE Software could allow an authenticated, remote attacker to utilize parts of the web UI for which they are not authorized.The vulnerability is due to insufficient authorization of web UI access requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the web UI. A successful exploit could allow the attacker to utilize parts of the web UI for which they are not authorized. This could allow a Read-Only user to perform actions of an Admin user.

Frequently asked questions

What is CVE-2020-3400?: A vulnerability in the web UI feature of Cisco IOS XE Software could allow an authenticated, remote attacker to utilize parts of the web UI for which they are not authorized.The vulnerability is due to insufficient authorization of web UI access requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the web UI. A successful exploit could allow the attacker to utilize parts of the web UI for which they are not authorized. This could allow a Read-Only user to perform actions of an Admin user.
How severe is CVE-2020-3400?: CVE-2020-3400 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-3400 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-3400?: CVE-2020-3400 primarily affects Cisco Ios Xe. In total, 15 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-3400?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-3400 published?: CVE-2020-3400 was published on 2020-09-24 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webui-auth-bypass-6j2BYUc7

Affected products (15)

cpe:2.3:o:cisco:ios_xe:16.2.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.1a:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.3:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.4:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.5:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.5b:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.6:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.7:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.8:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.9:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.10:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.11:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:17.2.1t:*:*:*:*:*:*:*

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