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Spring BootFramework / library · VMware

CVE-2026-40976

CRITICAL · 9.1 CVSS v3.1 Published 2026-04-28
Fix available
A fix is available. Upgrade to 4.0.6 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In certain circumstances, Spring Boot's default web security is ineffective allowing unauthorized access to all endpoints. For an application to be vulnerable, it must: be a servlet-based web application; have no Spring Security configuration of its own and rely on the default web security filter chain; depend on spring-boot-actuator-autoconfigure; not depend on spring-boot-health. If any of the above does not apply, the application is not vulnerable. Affected: Spring Boot 4.0.0–4.0.5; upgrade to 4.0.6 or later per vendor advisory.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Spring Boot 4.0.0-4.0.5 has a security bypass where the default web security filter chain becomes ineffective under specific conditions: when the app is servlet-based, lacks custom Spring Security configuration, includes spring-boot-actuator-autoconfigure, and excludes spring-boot-health. This allows unauthenticated attackers to access all endpoints.

MitigationUpgrade Spring Boot to version 4.0.6 or later, or implement explicit Spring Security configuration to replace the default filter chain.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Spring BootFramework / library
Affected:>= 4.0.0, < 4.0.6

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Spring Boot version
    Inspect your pom.xml, build.gradle, or run 'mvn spring-boot:parent' to find the Spring Boot version. Look for the <parent><version> element in pom.xml or the 'springBootVersion' variable in build.gradle.
    Affected if Version is 4.0.0, 4.0.1, 4.0.2, 4.0.3, 4.0.4, or 4.0.5
  2. Verify spring-boot-actuator-autoconfigure dependency
    Search your dependency management file (pom.xml or build.gradle) for 'spring-boot-actuator-autoconfigure' in the dependencies section.
    Affected if The dependency is present in your build configuration
  3. Confirm spring-boot-health is excluded
    Search your pom.xml for <exclusions> containing 'spring-boot-health' or check build.gradle for an exclude statement for 'spring-boot-health'. Also verify the dependency is not listed in your dependencies section.
    Affected if spring-boot-health is explicitly excluded or not present as a dependency while actuator-autoconfigure is included
  4. Check for custom Spring Security configuration
    Look for a @Configuration class annotated with @EnableWebSecurity or any WebSecurityConfigurerAdapter implementation in your source code. Also check for security-related properties in application.properties/yml under spring.security.*
    Affected if No custom Spring Security configuration exists - the application relies on Spring Boot's default security behavior
  5. Confirm servlet-based application type
    Verify your application uses javax.servlet.* or jakarta.servlet.* APIs. Check for @WebServlet annotations, servlet registrations in code, or a web.xml file. Spring Boot Web (Spring MVC) applications using the default auto-configuration are servlet-based.
    Affected if The application is servlet-based (standard Spring Boot web application, not reactive)

You are affected if your Spring Boot version is 4.0.0-4.0.5, you have spring-boot-actuator-autoconfigure without spring-boot-health, use default security with no custom Spring Security config, and run a servlet-based application.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.0.6 or later
Fixed in 4.0.6
Interim mitigation

Upgrade Spring Boot to version 4.0.6 or later, or implement explicit Spring Security configuration to replace the default filter chain.

Recommended fix High confidence

Spring Boot 4.0.6 or later

  1. Identify the current Spring Boot version in your project's pom.xml (for Maven) or build.gradle (for Gradle)
  2. Update the spring-boot.version property or plugin version to 4.0.6 or later
  3. Verify that spring-boot-actuator-autoconfigure and spring-boot-starter-security dependencies are at compatible versions
  4. Rebuild the application with the updated dependencies
  5. Test that all endpoints remain accessible as expected and that security filtering functions correctly
  6. Deploy the rebuilt application to production
Caveat Review the Spring Boot 4.0.6 release notes for any breaking changes from 4.0.0-4.0.5, particularly regarding actuator and security behavior changes

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Spring Boot Scoped from the published advisory
  • Consultation8.0 h
  • Implementation12.0 h
  • Testing16.0 h
  • Review / QA8.0 h
44.0 hours of engineering $7,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $12,160.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-40976 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data