CVE-2020-1758Network attack vector

Email interception via unchecked SMTP certificate hostname

Published May 15, 2020 · Updated Aug 4, 2024

Improper certificate validation in Red Hat build of Keycloak before 10.0.0 allows man-in-the-middle attackers to intercept SMTP email. DefaultEmailSenderProvider.setupTruststore fails to enable JavaMail server-identity checking, so TLS accepts a trusted certificate issued for another host. Exploitation requires control of the SMTP network path and an email-triggering action; intercepted messages can disclose sensitive links or content.

CVSS severity5.3
Medium
EPSS probability0.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in Red Hat build of Keycloak before 10.0.0 allows man-in-the-middle attackers to intercept SMTP email. DefaultEmailSenderProvider.setupTruststore fails to enable JavaMail server-identity checking, so TLS accepts a trusted certificate issued for another host. Exploitation requires control of the SMTP network path and an email-triggering action; intercepted messages can disclose sensitive links or content.

The record

CVE
CVE-2020-1758
Published
May 15, 2020
Updated
Aug 4, 2024
Vendor
Red Hat
Product
Red Hat build of Keycloak
Classifications
CWE-297, CWE-295, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 15, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=keycloak versions before 10.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Red Hat · Red Hat build of Keycloakversion=keycloak versions before 10.0.0

Published CVSS scores

4.3NIST National Vulnerability DatabaseAV:N/AC:M/Au:N/C:P/I:N/A:N
5.9NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
5.3Red Hat, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-297Improper Validation of Certificate with Host Mismatch
CWE-295Improper Certificate Validation
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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