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Vulnerability record · CVE-2020-1758 · published 15 May 2020

CVE-2020-1758: Redhat keycloak improper certificate validation vulnerability

Redhat · Keycloak

A flaw was found in Keycloak in versions before 10.0.0, where it does not perform the TLS hostname verification while sending emails using the SMTP server. This flaw allows an attacker to perform a man-in-the-middle (MITM) attack.

5.9 CVSS 3.1 Medium EPSS 0.91% · top 41.7% CWE-297 · CWE-297CWE-295 · Improper certificate validation
5.9CVSS 3.1 base score, v2 4.3
0.91%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

A flaw was found in Keycloak in versions before 10.0.0, where it does not perform the TLS hostname verification while sending emails using the SMTP server. This flaw allows an attacker to perform a man-in-the-middle (MITM) attack.

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

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-1758 Issue TrackingVendor Advisory
https://issues.redhat.com/browse/KEYCLOAK-13285 Permissions RequiredVendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-1758 Issue TrackingVendor Advisory
https://issues.redhat.com/browse/KEYCLOAK-13285 Permissions RequiredVendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2020-1758), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.