How severe is CVE-2019-5456?

CVE-2019-5456 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2019-5456 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-5456?

CVE-2019-5456 affects Ui Unifi Controller. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2019-5456?

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-2019-5456 published?

CVE-2019-5456 was published on 2019-07-30 and last updated on 2026-06-17.

CVE-2019-5456

CVE-2019-5456 is a high-severity vulnerability in Ui Unifi Controller with a CVSS 3.x base score of 8.1. 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-255.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 4.3
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-255
Affected product: Ui Unifi Controller
Published: 2019-07-30
Last modified: 2026-06-17

Description

SMTP MITM refers to a malicious actor setting up an SMTP proxy server between the UniFi Controller version <= 5.10.21 and their actual SMTP server to record their SMTP credentials for malicious use later.

Frequently asked questions

What is CVE-2019-5456?: SMTP MITM refers to a malicious actor setting up an SMTP proxy server between the UniFi Controller version <= 5.10.21 and their actual SMTP server to record their SMTP credentials for malicious use later.
How severe is CVE-2019-5456?: CVE-2019-5456 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2019-5456 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-5456?: CVE-2019-5456 affects Ui Unifi Controller. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2019-5456?: 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-2019-5456 published?: CVE-2019-5456 was published on 2019-07-30 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:ui:unifi_controller:*:*:*:*:*:*:*:*

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