CVE-2026-41081: Improper Handling of TLS Client Authentication Failure Leading to Anonymous Principal Assignment in Apache Storm Versions Affected: up to 2.8.7 Desc...

Description

Improper Handling of TLS Client Authentication Failure Leading to Anonymous Principal Assignment in Apache Storm Versions Affected: up to 2.8.7 Description: When TLS transport is enabled in Apache Storm without requiring client certificate authentication (the default configuration), the TlsTransportPlugin assigns a fallback principal (CN=ANONYMOUS) if no client certificate is presented or if certificate verification fails. The underlying SSLPeerUnverifiedException is caught and suppressed rather than rejecting the connection. This fail-open behavior means an unauthenticated client can establish a TLS connection and receive a valid principal identity. If the configured authorizer (e.g., SimpleACLAuthorizer) does not explicitly deny access to CN=ANONYMOUS, this may result in unauthorized access to Storm services. The condition is logged at debug level only, reducing visibility in production. Impact: Unauthenticated clients may be assigned a principal identity, potentially bypassing authorization in permissive or misconfigured environments. Mitigation: Users should upgrade to 2.8.7 in which TLS authentication failures are handled in a fail-closed manner. Users who cannot upgrade immediately should: - Enable mandatory client certificate authentication (nimbus.thrift.tls.client.auth.required: true) - Ensure authorization rules explicitly deny access to CN=ANONYMOUS - Review all ACL configurations for implicit default-allow behavior

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

0.29%

20.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-287

Affected Software

Vendor	Product	Versions
Apache	Storm	< 2.8.7

References

https://lists.apache.org/thread/plxx5l29dvplk5rwzdcq53rdfl6v4gs8Mailing List, Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/04/25/3Mailing List, Third Party Advisory

Timeline

Published: Apr 27, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-41081?

Improper Handling of TLS Client Authentication Failure Leading to Anonymous Principal Assignment in Apache Storm Versions Affected: up to 2.8.7 Description: When TLS transport is enabled in Apache Storm without requiring client certificate authentication (the default configuration), the TlsTransportPlugin assigns a fallback principal (CN=ANONYMOUS) if no client certificate is presented or if certificate verification fails. The underlying SSLPeerUnverifiedException is caught and suppressed rather than rejecting the connection. This fail-open behavior means an unauthenticated client can establish a TLS connection and receive a valid principal identity. If the configured authorizer (e.g., SimpleACLAuthorizer) does not explicitly deny access to CN=ANONYMOUS, this may result in unauthorized access to Storm services. The condition is logged at debug level only, reducing visibility in production. Impact: Unauthenticated clients may be assigned a principal identity, potentially bypassing authorization in permissive or misconfigured environments. Mitigation: Users should upgrade to 2.8.7 in which TLS authentication failures are handled in a fail-closed manner. Users who cannot upgrade immediately should: - Enable mandatory client certificate authentication (nimbus.thrift.tls.client.auth.required: true) - Ensure authorization rules explicitly deny access to CN=ANONYMOUS - Review all ACL configurations for implicit default-allow behavior

How severe is CVE-2026-41081?

CVE-2026-41081 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.

How do I fix CVE-2026-41081?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.