Security readout for executives and security teams
Plain-English summary
Some Spring Boot 4.0 applications may unintentionally expose all endpoints when relying on default web security. The issue applies only to a narrow setup: servlet-based, no custom Spring Security configuration, actuator autoconfigure present, and spring-boot-health absent. Matching internet-facing services should be treated as urgent because unauthorized users could access protected functionality or data.
Executive priority
Critical priority for teams using Spring Boot 4.0.x. The vulnerable condition is specific, so first triage should identify matching applications. If a match is internet-facing or handles sensitive data, patch promptly and confirm endpoint access controls after upgrade.
Technical view
CVE-2026-40976 is an authorization bypass in Spring Boot 4.0.0 through 4.0.5 default web security. In the specified dependency and configuration combination, the default security filter chain can be ineffective, allowing unauthenticated network access to all endpoints. CVSS 3.1 is 9.1: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Fixed in 4.0.6 or later.
Likely exposure
Likely exposure is narrow but high impact: servlet-based Spring Boot 4.0.0-4.0.5 applications with no custom Spring Security, spring-boot-actuator-autoconfigure present, and spring-boot-health absent. Applications failing any listed condition are stated as not vulnerable in the source bundle.
Exploitation context
The source bundle does not report active exploitation, and KEV status is false. The vulnerability is remotely reachable, requires no privileges or user interaction, and could expose all endpoints when the vulnerable configuration is present. No exploit details are provided here.
Researcher notes
The vulnerability maps to CWE-305 and CWE-862. Do not assume all Spring Boot 4.0 applications are affected; the vendor-described preconditions are central. The provided sources name an upgrade path but do not include additional compensating controls beyond checking vendor guidance.
Mitigation direction
- Upgrade affected Spring Boot applications to 4.0.6 or later.
- Review Spring's vendor advisory for current remediation guidance.
- Add explicit Spring Security configuration where appropriate.
- Prioritize internet-facing services and administrative endpoints first.
Validation and detection
- Inventory Spring Boot applications running versions 4.0.0 through 4.0.5.
- Confirm whether each application is servlet-based.
- Check for custom Spring Security configuration.
- Review dependencies for spring-boot-actuator-autoconfigure and absence of spring-boot-health.
- Verify upgraded services are running Spring Boot 4.0.6 or later.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-305: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-862: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-40976 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N3.95.2vmwareCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N3.95.2redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
9.1CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Base CVSS 3.1 score
9.1CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-04-28T00:01:23.121Z: Reported to Red Hat.
- 2026-04-27T23:34:51.422Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://spring.io/security/cve-2026-40976CVE reference, vmware
- https://access.redhat.com/security/cve/CVE-2026-40976CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2463322CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40976.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Authentication Bypass by Primary Weakness
Authentication Bypass by Primary Weakness represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Missing Authorization
Missing Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.