CVE-2026-40971

Broker impersonation via disabled TLS hostname verification

Published Apr 27, 2026 · Updated Apr 27, 2026

Improper certificate validation in Spring Boot 3.5.0 through 3.5.13 and 4.0.0 through 4.0.5 allows attackers to impersonate RabbitMQ brokers. RabbitMQ auto-configuration passes an SSL bundle to the connection factory without consistently applying spring.rabbitmq.ssl.verify-hostname, so the TLS peer's certificate name is not checked. Reachability requires an application configured with a RabbitMQ SSL bundle and an attacker able to interpose on its broker connection; accepted mismatched certificates expose broker traffic to disclosure, modification, or interruption.

CVSS severity5.0
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in Spring Boot 3.5.0 through 3.5.13 and 4.0.0 through 4.0.5 allows attackers to impersonate RabbitMQ brokers. RabbitMQ auto-configuration passes an SSL bundle to the connection factory without consistently applying spring.rabbitmq.ssl.verify-hostname, so the TLS peer's certificate name is not checked. Reachability requires an application configured with a RabbitMQ SSL bundle and an attacker able to interpose on its broker connection; accepted mismatched certificates expose broker traffic to disclosure, modification, or interruption.

The record

CVE
CVE-2026-40971
Published
Apr 27, 2026
Updated
Apr 27, 2026
Vendor
Spring
Product
Spring Boot
Classifications
CWE-295, T1557
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.5.0 <3.5.14
  2. Affected versionversion=4.0.0 <4.0.6

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Spring · Spring Bootversion=3.5.0 <3.5.14; version=4.0.0 <4.0.6

Published CVSS scores

5.0VMwareCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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