CVE-2026-40992: Spring Boot · Improper Certificate Validation
Affects Spring BootSource CVE Database V5
Not known to be exploited · CVSS 5.0 Medium · fixed in 4.0.6.1 : update Spring Boot when convenient.
Data as of 29 Oct 2026, 19:04 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 4.0.6.1, 3.5.14.1, 3.4.17
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:LExploitation evidence
Disclosed: evidence found.
CVE published 11 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade Spring Boot to 4.0.6.1, 3.5.14.1 or 3.4.17.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| SpringSpring Boot | Affected
| Fixed in
|
| SpringSpring Boot | Affected
| Fixed in
|
| SpringSpring Boot | Affected
| Fixed in
|
Mavenorg.springframework.boot/spring-bootpkg:maven/org.springframework.boot/spring-bootOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
To mitigate this vulnerability, applications should explicitly enable hostname verification by setting the JavaMail property spring.mail.properties.mail.smtp.ssl.checkserveridentity=true in their configuration. This setting disables the vulnerability by enforcing proper certificate validation. Monitor the vendor advisory for any future official fixes or updates.
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.