CVE-2020-1758
Improper Certificate Validation and Improper Validation of Certificate with Host Mismatch in 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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
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.
- Record
CVE-2020-1758- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-297
- Updated
- 2026-11-02
EUVDEUVD-2022-0953
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.
- Record
EUVD-2022-0953- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-c597-f74m-jgc2
Improper Certificate Validation and Improper Validation of Certificate with Host Mismatch in 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.
- Record
GHSA-c597-f74m-jgc2- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-295, CWE-297
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2020-1758- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N - CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 2.0
- 4.3 Medium
AV:N/AC:M/Au:N/C:P/I:N/A:N - Weakness
- CWE-297, CWE-295
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2020-1758- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVGHSA-c597-f74m-jgc2
Improper Certificate Validation and Improper Validation of Certificate with Host Mismatch in 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.
- Record
GHSA-c597-f74m-jgc2- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-295, CWE-297
- Updated
- 2026-11-02
OSVRHSA-2020:2106
Red Hat Security Advisory: Red Hat Single Sign-On 7.3.8 security update on RHEL 6
- Record
RHSA-2020:2106- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVRHSA-2020:2107
Red Hat Security Advisory: Red Hat Single Sign-On 7.3.8 security update on RHEL 7
- Record
RHSA-2020:2107- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVRHSA-2020:2108
Red Hat Security Advisory: Red Hat Single Sign-On 7.3.8 security update on RHEL 8
- Record
RHSA-2020:2108- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
org.keycloak:keycloak-parentMaven |
before 10.0.0 | 10.0.0 |
org.keycloak:keycloak-parentMaven |
before 10.0.0, plus listed versions 1.0-alpha-11.0-alpha-1-120620131.0-alpha-21.0-alpha-31.0-alpha-4 Show 45 moreShow less1.0-beta-11.0-beta-1-201505211.0-beta-1-201505231.0-beta-21.0-beta-31.0-beta-41.0-final1.0-rc-11.0-rc-21.0.1.Final1.0.2.Final1.0.3.Final1.0.4.Final1.0.5.Final1.1.0.Beta11.1.0.Beta21.1.0.Final1.1.1.Final1.2.0.Beta11.2.0.CR11.2.0.Final1.3.0.Final1.3.1.Final1.4.0.Final1.5.0-Final1.5.0.Final1.5.1.Final1.6.0.Final1.6.1.Final1.7.0.CR11.7.0.Final1.8.0.Alpha11.8.0.CR11.8.0.CR21.8.0.CR31.8.0.Final1.8.1.Final1.9.0.CR11.9.0.Final1.9.1.Final1.9.2.Final1.9.3.Final1.9.4.Final1.9.5.Final1.9.7.Final |
10.0.0 |
rh-sso7-keycloakRed Hat:red_hat_single_sign_on:7::el6 From an advisory covering 3 CVEs |
before 0:4.8.20-1.Final_redhat_00001.1.el6sso | 0:4.8.20-1.Final_redhat_00001.1.el6sso |
rh-sso7-keycloak-serverRed Hat:red_hat_single_sign_on:7::el6 From an advisory covering 3 CVEs |
before 0:4.8.20-1.Final_redhat_00001.1.el6sso | 0:4.8.20-1.Final_redhat_00001.1.el6sso |
rh-sso7-keycloakRed Hat:red_hat_single_sign_on:7::el7 From an advisory covering 3 CVEs |
before 0:4.8.20-1.Final_redhat_00001.1.el7sso | 0:4.8.20-1.Final_redhat_00001.1.el7sso |
rh-sso7-keycloak-serverRed Hat:red_hat_single_sign_on:7::el7 From an advisory covering 3 CVEs |
before 0:4.8.20-1.Final_redhat_00001.1.el7sso | 0:4.8.20-1.Final_redhat_00001.1.el7sso |
rh-sso7-keycloakRed Hat:red_hat_single_sign_on:7::el8 From an advisory covering 3 CVEs |
before 0:4.8.20-1.Final_redhat_00001.1.el8sso | 0:4.8.20-1.Final_redhat_00001.1.el8sso |
rh-sso7-keycloak-serverRed Hat:red_hat_single_sign_on:7::el8 From an advisory covering 3 CVEs |
before 0:4.8.20-1.Final_redhat_00001.1.el8sso | 0:4.8.20-1.Final_redhat_00001.1.el8sso |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| aliases, products | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-1758 is a medium vulnerability (CVSS 5.3) in Keycloak, published May 15, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.93%, the 60th percentile. Fixed in org.keycloak:keycloak-parent 10.0.0.
References
bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-1758
issues.redhat.com/browse/KEYCLOAK-13285
nvd.nist.gov/vuln/detail/CVE-2020-1758
github.com/advisories/GHSA-c597-f74m-jgc2
access.redhat.com/errata/RHSA-2020:2106
Show 20 moreShow less
security.access.redhat.com/data/csaf/v2/advisories/2020/rhsa-2020_2106.json
cve.org/CVERecord?id=CVE-2020-1718
Left out here: 60 versions. The JSON record has them.