Description

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 Spring Products and Versions

Spring Boot:

• 4.0.0 - 4.0.6
• 3.5.0 - 3.5.14
• 3.4.0 - 3.4.16

Mitigation

Users of affected versions should upgrade to the corresponding fixed version.

No further mitigation steps are necessary.

References

• https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L&version=3.1

Credit

[Yu Bao (@August829])](https://github.com/August829) - [email protected] – who works for paypal.com.

History

• 2026-06-10: Initial vulnerability report published.
• 2026-06-12: Add credit and clarify that no versions other than those listed are affected.