CVE-2026-40992 Mail Auto-Configuration Does Not Enable SSL Hostname Verification
Spring Boot mail auto-configuration fails to verify SSL hostnames, allowing man-in-the-middle attacks unless explicitly configured.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-40992?
CVE-2026-40992 is a medium-severity vulnerability in Spring Boot, published on 11 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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 versions: Spring Boot 4.0.0 through 4.0.6; 3.5.0 through 3.5.14; 3.4.0 through 3.4.16.
Weakness: CWE-295
Which versions are affected by CVE-2026-40992?
6 open source packages ship an affected version, including org.springframework.boot:spring-boot-starter-mail. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
org.springframework.boot:spring-boot-starter-mail Maven | From 3.4.0 to 3.4.16 | None |
org.springframework.boot:spring-boot-starter-mail Maven | From 3.4.0 to 3.4.16 | None |
org.springframework.boot:spring-boot-starter-mail Maven | From 3.5.0 | 3.5.15 |
org.springframework.boot:spring-boot-starter-mail Maven | From 3.5.0 | 3.5.15 |
org.springframework.boot:spring-boot-starter-mail Maven | From 4.0.0 | 4.0.7 |
org.springframework.boot:spring-boot-starter-mail Maven | From 4.0.0 | 4.0.7 |
Products include Vmware Spring Boot.
How do I fix CVE-2026-40992?
Upgrade org.springframework.boot:spring-boot-starter-mail to a fixed version for your release line: 3.5.15 or 4.0.7.
Is CVE-2026-40992 being exploited?
There is no known exploitation of CVE-2026-40992 in the wild and no public exploit code.
Other vulnerabilities in Spring Boot
- CVE-2023-20873 Spring Boot Security Bypass with Wildcard Pattern Matching on Cloud Foundry
- CVE-2026-40976 Spring Boot's default security filter chain has no authorization rule with Actuator but without Health
- CVE-2026-22731 Authentication Bypass under Actuator Health groups paths
- CVE-2026-22733 Authentication Bypass under Actuator CloudFoundry endpoints
- CVE-2022-27772 Temporary Directory Hijacking to Local Privilege Escalation Vulnerability in org.springframework.boot:spring-boot
Sources
Also known as CLEANSTART-2026-CZ64223, ECHO-2654-53dc-59a6, GHSA-9wxp-w4px-32vh, ROOT-APP-MAVEN-CVE-2026-40992.