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CVE-2026-40992

MEDIUM 5

Published 2026-06-11 · Last modified 2026-06-23

Spring Boot's Mail auto-configuration does not enable hostname verification. Applications that set the relevant JavaMail property, such as spring.mail.properties.mail.smtp.ssl.checkserveridentity=true, are not affected. Affected versions: Spring Boot 4.0.0 through 4.0.6; 3.5.0 through 3.5.14; 3.4.0 through 3.4.16.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.1%chance of exploitation in 30 days · 2nd percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

5CVSS 3.1 · MEDIUM

  • ConfidentialityLow
  • IntegrityLow
  • AvailabilityLow

What an attacker needs

  • ⚠Access: Must sit on the same / adjacent network
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ⚠Complexity: Needs a race window or specific setup

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-40992/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-40992/poc.json

Affected

Vendors Spring

Products Spring Boot

Weakness (CWE)

  • CWE-295: : Improper Certificate Validation

CVSS vector

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

All CVSS metrics

  • MEDIUM 5 v3.1 · CNA Primary
    CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
  • MEDIUM 5 v3.1 · NVD Secondary
    CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

References

Technical & other

Sources: NVD · CVE.org · EPSS