Spring Security Advisories

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Reactor Netty may incorrectly route traffic due to DNS resolver reuse

LOW | AUGUST 20, 2026 | CVE-2026-47843

Description

In specific scenarios involving multiple clients with different DNS resolver configurations, Reactor Netty may incorrectly reuse a previously configured DNS resolver. In order for this to happen, the application must dynamically create multiple clients (such as HttpClient or TcpClient) that rely on different custom configuration. This can lead to traffic being routed to unintended destinations.

Affected Spring Products and Versions

Reactor Netty:

  • 1.3.0 - 1.3.6
  • 1.1.0 - 1.2.18
  • 1.0.52 and earlier

Mitigation

Users of affected versions should upgrade to the corresponding fixed version.
Fix versionAvailability
1.3.7OSS
1.3.6.1Enterprise Support Only
1.2.19Enterprise Support Only
1.0.53Enterprise Support Only

No further mitigation steps are necessary.

References

History

  • 2026-08-20: Initial vulnerability report published.

Reporting a vulnerability

To report a security vulnerability for a project within the Spring portfolio, see the Security Policy

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