CVE-2026-40976: Spring Boot's default security filter chain has no authorization rule with Actuator but without Health

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.5%, percentile 44: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 44% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes org.springframework.boot:spring-boot (Maven) >= 4.0.0, < 4.0.6, fixed in 4.0.6. Check your lockfile, including transitive dependencies.

What it is

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.

From the GitHub advisory

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.

Weakness type: CWE-862, CWE-305.

Product: org.springframework.boot:spring-boot (Maven) · Assigned by: vmware · Published: 2026-04-27

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.54% probability of exploitation activity in the next 30 days; percentile 44.

Timeline

• 2026-04-27 — CVE record published by vmware
• 2026-04-28 — GitHub-reviewed advisory GHSA-8v8j-3hxp-93wr published (critical)
• 2026-07-15 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-8v8j-3hxp-93wr github.com
2. CVE.org record CVE-2026-40976 cve.org
3. NVD entry CVE-2026-40976 nvd.nist.gov

Other references from the CVE record and advisory

1. spring.io spring.io
2. access.redhat.com access.redhat.com
3. RHBZ#2463322 bugzilla.redhat.com
4. security.access.redhat.com security.access.redhat.com

Critical Maven advisories · Today’s Security Digest