Vulnerability in Spring Boot

CVE-2026-40970

When configured to use an SSL bundle, Spring Boot's Elasticsearch auto-configuration does not perform hostname verification when connecting to the Elasticsearch server. Affected: Spring Boot 4.0.0–4.0.5; upgrade to 4.0.6 or later per vendor advisory.

Vulnerability class: Improper Certificate Validation

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.0 (Medium). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.002 (10.3th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 10th percentile — 10.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-40970: held from 0.001 to 0.002.

EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-40970?
CVE-2026-40970 is a medium-severity vulnerability in Spring Boot, classified under Improper Certificate Validation. CVSS score: 5.0/10. Published 2026-04-27.
How severe is CVE-2026-40970?
Medium severity. CVSS v3 base score is 5.0 out of 10.