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VulnerabilityPublished Updated

CVE-2026-40976: Spring Boot · Missing Authorization

Affects Spring BootSource CVE Database V5

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Not known to be exploited · CVSS 9.1 Critical : upgrade to 4.0.6 as a priority.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.

Contested

Critical score, yet low EPSS after six months
EPSS
0.4% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.0.6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade Spring Boot to 4.0.6.

Affected software

ProductAffectedFixed in
SpringSpring BootAffected
  • >=4.0.0 <4.0.6
Fixed in
  • 4.0.6
Mavenorg.springframework.boot/spring-bootpkg:maven/org.springframework.boot/spring-bootOther threatsAffected
  • 4.0.0 – 4.0.5
6 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available by upgrading to Spring Boot version 4.0.6 or later as per the vendor advisory. Applications should verify their Spring Security configurations and avoid relying solely on the default security filter chain if they depend on spring-boot-actuator-autoconfigure and do not depend on spring-boot-health. Consult the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-40976 for detailed remediation guidance.

Description

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.

References

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