CVE-2026-40992: Spring Boot's Mail auto-configuration does not enable hostname verification

Routine

MEDIUM 5.0UPGRADE

CVE-2026-40992 is a medium-severity flaw (CVSS 5.0) affecting spring boot. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.0 (Medium)
Attack vector	Adjacent network
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.1% (top 98%)
CISA exploited list	No
Weakness	CWE-295
Published	2026-06-11
Last modified	2026-09-04

Publisher (CNA): VMware · Vendor: vmware

Last updated 2026-09-04 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-11 07:16 UTCPublished CVE record published
2026-09-04 18:05 UTCUpdated Record last modified

vmware spring boot UPGRADE

Affected: >= 3.4.0 and < 3.4.17 · >= 3.5.0 and < 3.5.14.1 · >= 4.0.0 and < 4.0.6.1

Fixed in: 3.4.17, 3.5.14.1, 4.0.6.1

Safe to downgrade to: a release before 3.4.0

1. Check installed version

apt-cache policy spring-boot || rpm -q spring-boot || spring-boot --version

2. UPGRADE to 3.4.17 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade spring-boot

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade spring-boot

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.4.0 (Debian / Ubuntu)

apt-cache madison spring-boot sudo apt install spring-boot=<VERSION_BEFORE_3.4.0> sudo apt-mark hold spring-boot

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list spring-boot sudo dnf downgrade spring-boot-<VERSION_BEFORE_3.4.0> sudo dnf versionlock add spring-boot

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-40992?

spring boot: upgrade to 3.4.17, 3.5.14.1, 4.0.6.1. Exact commands for each OS are on this page.

Is CVE-2026-40992 being exploited?

CVE-2026-40992 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-40992 affect?

CVE-2026-40992 affects spring boot. Severity is medium (CVSS 5.0). 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:

How urgent is CVE-2026-40992?

Priority 18/100. No elevated risk signals yet.

Software pages

Spring Framework vulnerabilities · VMware vulnerabilities

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References

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