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CVE-2026-40992· NVD / CVE Program· CNA vmware

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.

MediumCVSS 5.0 · v3.1—No exploit Fix available
Published
Jun 11, 2026
Updated
Sep 4, 2026
EPSS
0.2% · 7th percentile
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Report tools

JSON

Action score

20

Monitor

Low priority for now.

CVSS
20 / 40 · 5.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · vmware
5.0
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

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Affected systems

VendorProduct
vmwarespring boot

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • vmware spring boot3.4.0 and later · before 3.4.17
  • vmware spring boot3.5.0 and later · before 3.5.14.1
  • vmware spring boot4.0.0 and later · before 4.0.6.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (vmware). Independent of NVD's CPE analysis and usually ahead of it.

  • Spring Spring Boot

    • 4.0.0 and later · before 4.0.6.1affected
    • 3.5.0 and later · before 3.5.14.1affected
    • 3.4.0 and later · before 3.4.17affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Mavenorg.springframework.boot:spring-boot-starter-mailfrom 3.4.0 · up to and including 3.4.16—
Mavenorg.springframework.boot:spring-boot-starter-mailfrom 3.5.0 · before 3.5.153.5.15
Mavenorg.springframework.boot:spring-boot-starter-mailfrom 4.0.0 · before 4.0.74.0.7

Same product

vmware: all records

Other highest-scoring records for the same primary product.

  • CVE-2017-8046Malicious PATCH requests submitted to servers using Spring Data REST versions prior to 2.6.9 (Ingalls SR9), versions prior to 3.0.1 (Kay SR1
    61This week
  • CVE-2021-26987Element Plug-in for vCenter Server incorporates SpringBoot Framework.
    40Plan
  • CVE-2026-40974Spring Boot's Cassandra auto-configuration does not perform hostname verification when establishing an SSL connection to Cassandra.
    39Monitor
  • CVE-2023-20873In Spring Boot versions 3.0.0 - 3.0.5, 2.7.0 - 2.7.10, and older unsupported versions, an application that is deployed to Cloud Foundry coul
    39Monitor
  • CVE-2026-40976In certain circumstances, Spring Boot's default web security is ineffective allowing unauthorized access to all endpoints.
    36Monitor
  • CVE-2026-40971When configured to use an SSL bundle, Spring Boot's RabbitMQ auto-configuration does not perform hostname verification when connecting to th
    36Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Maven:org.springframework.boot:spring-boot-starter-mail3.5.15Package registry (OSV)
Maven:org.springframework.boot:spring-boot-starter-mail4.0.7Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-4097445 days apartSpring Boot's Cassandra auto-configuration does not perform hostname verification when establishing an SSL connection to Cassandra.
    39Monitor
  • CVE-2026-4097145 days apartWhen configured to use an SSL bundle, Spring Boot's RabbitMQ auto-configuration does not perform hostname verification when connecting to th
    36Monitor
  • CVE-2026-4097045 days apartWhen configured to use an SSL bundle, Spring Boot's Elasticsearch auto-configuration does not perform hostname verification when connecting
    27Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • No account or password is required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
low · data can be read
Integrity
low · data or configuration can be modified
Availability
low · the service can be disrupted
Attack vector
Adjacent
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
Low
Availability impact
Low

Weakness class (CWE)

CWE-295 · Improper Certificate Validation

CVSS vector

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

nvd-secondary

Root cause

A certificate validation error is silently swallowed instead of terminating the connection. Often, code added for a test environment makes its way into production.

The bug in code

The whole CWE-295 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

kotlin
override fun checkServerTrusted(chain: Array<X509Certificate>, type: String) {  // Left empty for the test environment}

Fixed

kotlin
val client = OkHttpClient.Builder()  .certificatePinner(    CertificatePinner.Builder()      .add("api.sirius.example", "sha256/…")      .build()  ).build()

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records