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VulnerabilityPublished

CVE-2026-40970: Spring Boot · Improper Certificate Validation

Affects Spring BootSource CVE Database V5

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Not known to be exploited · CVSS 5.0 Medium : upgrade to 4.0.6 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
5.0Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.0.6
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  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), 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

Upgrade affected Spring Boot versions from 4.0.0–4.0.5 to version 4.0.6 or later as recommended by the vendor. Patch status is confirmed by the vendor advisory indicating an official fix is available in version 4.0.6. No additional mitigations are specified.

Description

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.

References

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