# CVE-2026-105926: Apache Pulsar broker authorization bypass in schema commands

Source: https://junglewise.ai/threats/cve-2026-105926-the-pulsar-broker-serves-two-schema-commands-on-its-binary  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-21. Updated: 2026-10-21  
License: CC BY 4.0 with a link back

CVE-2026-105926 · Severity: info · Published 2026-10-21

Apache Pulsar's message broker handles schema management commands without properly checking if the authenticated client has permission to access the target topic. An attacker with valid credentials but no permissions can view schema definitions in other namespaces or tenants, or register incompatible schema versions that disrupt legitimate producers and consumers. This only affects deployments with authentication and authorization enabled.

Technologies: [Apache Pulsar](https://junglewise.ai/threats/technologies/pulsar). Vendors: [Apache](https://junglewise.ai/threats/vendors/apache).

## Quick answers

**Is CVE-2026-105926 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-105926 being exploited in the wild.

**How severe is CVE-2026-105926?** Informational severity, published 21 October 2026.

**Which products and versions are affected?** Apache Pulsar 2.2.0 through 4.0.13, 4.1.0 through 4.1.3, 4.2.0 through 4.2.4.

**Is there a fix for CVE-2026-105926?** Yes: fixed in Apache Pulsar 4.0.14, 4.1.4, 4.2.5 and later. Until then: Ensure authentication and authorization are enabled in your Pulsar deployment. Restrict network access to the Pulsar broker's binary protocol port to trusted clients only until you can upgrade.</anigation>
<parameter name="timeline">[{"kind":"disclosed","at":"2026-10-21"}] Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-105926 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-105926?** Check whether you run Apache Pulsar at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Apache Pulsar 4.0.14, 4.1.4, 4.2.5 and later

Ensure authentication and authorization are enabled in your Pulsar deployment. Restrict network access to the Pulsar broker's binary protocol port to trusted clients only until you can upgrade.</anigation>
<parameter name="timeline">[{"kind":"disclosed","at":"2026-10-21"}]

## Technical details

The Pulsar broker's GetSchema and GetOrCreateSchema binary protocol commands perform authentication checks but skip authorization checks that are applied to other topic operations. An authenticated but unprivileged client can invoke these commands directly on any topic without the broker verifying lookup or produce permissions. The standard Pulsar client masks this issue by performing authorized lookups before sending these commands, but raw protocol clients bypass that protection.

## Affected products

- Apache Pulsar 2.2.0 through 4.0.13, 4.1.0 through 4.1.3, 4.2.0 through 4.2.4

## Related threats

- [Apache Pulsar path traversal in package management filesystem storage](https://junglewise.ai/threats/cve-2026-105945-the-pulsar-packages-management-service-can-be-configured-to)
- [Apache Pulsar proxy authorization bypass in multi-role token provider](https://junglewise.ai/threats/cve-2026-105942-when-a-configured-proxy-role-sends-a-request-to-the-broker-on)
- [Apache Pulsar subscription policy bypass in admin REST API](https://junglewise.ai/threats/cve-2026-105938-apache-pulsar-namespaces-can-restrict-which-roles-may-use-a)
- [Apache Pulsar cross-tenant data access via shadow topics](https://junglewise.ai/threats/cve-2026-105937-apache-pulsar-shadow-topics-pip-180-are-topics-that-read-the)
- [Apache Pulsar Functions worker REST API improper access control](https://junglewise.ai/threats/cve-2026-105936-the-pulsar-functions-worker-rest-api-provides-two-endpoints-that)