CVE-2026-105936

A vulnerability in Apache Pulsar's MultiRolesTokenAuthorizationProvider allows a client to be authorized with all roles listed in an unverified JWT claim. When anonymousUserRole is set and authentication fails but falls back to anonymous, an unauthenticated client can send a forged or unsigned token with arbitrary roles and be authorized, potentially gaining super-user access.

The Apache Pulsar Packages Management Service with the FileSystemPackagesStorageProvider did not validate the version component of a package name, which could contain URL-encoded path separators and parent directory references. This allowed the filesystem storage provider to resolve the version to a location belonging to a package in a different tenant or namespace, and the containment check inside the storage directory did not prevent the access. An authenticated user with the packages permission on any namespace could download, overwrite or delete packages in other tenants or namespaces.

Apache Pulsar contains two flaws in the authorization of requests forwarded by a proxy on behalf of another user. The first authorizes the original principal using the proxy's authentication data (affecting e.g. MultiRolesTokenAuthorizationProvider), and the second skips the original principal check for tenant admin operations when the proxy role is a tenant admin. This may allow users to perform operations beyond their own permissions.

Apache Pulsar did not apply subscription policies (Prefix subscription authentication mode or subscription permissions) in several admin REST API operations acting on subscriptions: clearing the backlog (for a named subscription and for all subscriptions), unsubscribe, and expiring messages for all subscriptions of a topic. An authenticated user with consume permission on the namespace or topic could bypass these policies and clear the backlog, expire messages, or delete a subscription that the policies would deny to that user.

A vulnerability in Apache Pulsar affects the shadow topics mechanism (PIP-180). The broker authorizes the caller only against the topic being created or updated, not against the source topic named in the PULSAR.SHADOW_SOURCE property. This allows an authenticated user with permission to create topics or update topic properties in one tenant to bind a topic to a source topic in another tenant and read its retained messages.

The vulnerability affects the Apache Pulsar Functions Worker REST API trigger endpoint. The Worker publishes a message to the function's input topic using its own broker-client credentials rather than the caller's credentials, and does not verify that the caller is authorized to produce to that topic. Versions before 2.4.0 perform no caller authorization check for this endpoint at all.

Apache Pulsar broker versions 2.8.0 through 4.0.13 and 4.1.0 through 4.2.4 do not apply the tenant admin check to the caller for the truncate operation on a partitioned topic. Instead, the broker truncates each partition using its own internal admin client, so an authenticated user without tenant admin rights but with lookup permission can truncate any partitioned topic. This skips unacknowledged subscription backlog and permanently deletes older ledgers regardless of the namespace retention policy.

Apache Pulsar allows administrators to enforce end-to-end message encryption for all topics in a namespace via the encryption_required namespace policy. If loading a persistent topic fails during initialization (e.g., metadata store read error or topic-level policy load failure), the broker logs a warning, disables the encryption requirement for that topic, and completes the topic load as successful. As a result, an authenticated client with produce permissions can publish unencrypted messages that the broker accepts and stores, even though the namespace policy requires encryption.

The Apache Pulsar broker admin REST API endpoints for non-persistent topics (/admin/v2/non-persistent/.../entryFilters) do not perform the entry filters topic policy authorization check, unlike persistent topic endpoints. An authenticated user with produce or consume permission on a non-persistent topic can read, replace, or remove that topic's entry filter policy. This affects versions from 3.3.0 before 4.0.14 and from 4.1.0 before 4.2.5.

The Apache Pulsar broker exposes a transaction administration REST API under /admin/v3/transactions. When authentication and authorization are enabled, most read endpoints of this API verify only that the request is authenticated and that the broker serves the requested topic or transaction coordinator, without checking whether the caller is permitted to access the tenant, namespace or topic whose data is returned. As a result, any authenticated user, including one with no permissions, can read transaction coordinator and transaction information belonging to other tenants.