CVE-2026-105942

published 2026-10-21

CVE-2026-105942: When a configured proxy role sends a request to the broker on behalf of another user (the original principal), the broker is designed to authorize both the…

Priority P3 54 high 7.7 CVSS 4.0

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When a configured proxy role sends a request to the broker on behalf of another user (the original principal), the broker is designed to authorize both the proxy role and the original principal and to allow the request only if both are authorized, so that the original principal cannot exceed its own permissions. Two flaws weakened this check.

First, the original principal was authorized with the proxy's authentication data instead of its own. On the admin REST API of the broker and the functions worker, this applied to every proxied request. On the Pulsar binary protocol, it applied when the proxy did not forward the client's credentials to the broker, which was the default of the Pulsar proxy in the affected versions. Authorization providers that resolve permissions from the role name only, such as the default authorization provider, are not affected by this flaw. The multi-role token authorization provider (MultiRolesTokenAuthorizationProvider), added in Apache Pulsar 2.8.1, resolves roles from the role claim of the token in the authentication data it is given. When a proxy authenticates to the broker with its own token, the original principal was therefore authorized with all roles in the proxy's token. If any of those roles is a superuser or tenant admin role, any user whose requests are forwarded by that proxy can perform operations that need those permissions without holding them. Custom authorization providers that use the authentication data could be affected in a similar way.

Second, independently of the authorization provider, the tenant admin check of a proxied admin REST API request succeeded without checking the original principal when the proxy role was itself an admin role of the tenant. In deployments where a proxy role is a tenant admin, including with the default authorization provider, any user whose requests are forwarded by that proxy could perform tenant administration operations on that tenant. This behavior is present from 2.8.4 in the 2.8.

Affected

2 ranges

Vendor	Product	Version range	Fixed in
apache_software_foundation	apache_pulsar	>= 2.8.1 < 4.0.14	4.0.14
apache_software_foundation	apache_pulsar	>= 4.1.0 < 4.2.5	4.2.5

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CWE-863