Spring Boot Mail Auto-Config missing hostname verification (3.4-4.0)
CVE-2026-40992 Published on June 11, 2026
Mail Auto-Configuration Does Not Enable SSL Hostname Verification
Spring Boot's Mail auto-configuration does not enable hostname verification. Applications that set the relevant JavaMail property, such as spring.mail.properties.mail.smtp.ssl.checkserveridentity=true, are not affected.
Affected versions:
Spring Boot 4.0.0 through 4.0.6; 3.5.0 through 3.5.14; 3.4.0 through 3.4.16.
Vulnerability Analysis
Weakness Type
Improper Certificate Validation
The software does not validate, or incorrectly validates, a certificate. When a certificate is invalid or malicious, it might allow an attacker to spoof a trusted entity by interfering in the communication path between the host and client. The software might connect to a malicious host while believing it is a trusted host, or the software might be deceived into accepting spoofed data that appears to originate from a trusted host.
Products Associated with CVE-2026-40992
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Affected Versions
Spring Boot:- Version 4.0.0 and below 4.0.7 is affected.
- Version 3.5.0 and below 3.5.15 is affected.
- Version 3.4.0 and below 3.4.17 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.