--- id: "CVE-2026-105935" kind: "vulnerability" aliases: ["CVE-2026-105935"] title: "Apache Pulsar: Functions Worker trigger endpoint skips topic produce authorization" severity: "medium" cvss: 4.9 epss: 0.00398 exploited: false status: "open" category: "package" products: [] ecosystems: [] tags: ["apache-pulsar", "kubernetes", "package", "self-hosted"] not_affected_if: ["authorization-disabled", "no-functions-worker", "patched-version"] published_at: "2026-10-21T19:16:56+00:00" first_seen_at: "2026-10-23T21:57:29+00:00" updated_at: "2026-10-25T04:31:09+00:00" sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-105935", "first_seen_at": "2026-10-23T21:57:29+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-105935", "first_seen_at": "2026-10-24T13:15:54+00:00"}] --- # Apache Pulsar: Functions Worker trigger endpoint skips topic produce authorization The Pulsar Functions Worker REST trigger endpoint publishes caller-supplied messages to a function's input topic using the Worker's own broker identity, without checking that the caller may produce to that topic. An authenticated user with function-management rights in one namespace can inject messages into topics they cannot write to, including topics in other tenants. _Summary, check and fix written by a model from the sources; labelled as such._ ## How to check - Check the Apache Pulsar version in use, for example with `pulsar-admin brokers version` or the broker image tag; affected if below `4.0.14` on the 4.0.x line, or below `4.2.5` on the 4.1.x and 4.2.x lines, or any version before `2.4.0` with authorization enabled. - Check whether `authorizationEnabled` is set to true in the broker configuration and whether Functions Worker is running. - Review which roles hold the functions permission on each namespace, for example with `pulsar-admin namespaces permissions /`. ## Fix - Upgrade Apache Pulsar 4.0.x installations to at least `4.0.14`. - Upgrade Apache Pulsar 4.1.x and 4.2.x installations to at least `4.2.5`. - Upgrade anything older than `2.4.0` to a patched release, or restrict access to the Functions Worker REST API to trusted callers. - Until upgraded, limit the functions management permission on namespaces to trusted roles only. ## Timeline - 2026-10-23T21:57:29+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-105935 - 2026-10-24T13:15:54+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-105935 ## From the sources The Pulsar Functions Worker provides a REST API endpoint for triggering a function, which publishes a caller-supplied value to one of the function's configured input topics. The Functions Worker performs this publish with its own broker client, which authenticates with the Worker's configured broker-client credentials rather than the credentials of the API caller. When authorization is enabled, in Apache Pulsar 2.4.0 and later versions, the trigger endpoint checks only that the caller is authorized to perform function operations in the function's namespace. It does not check that the caller is authorized to produce to the input topic that the message is published to. Versions before 2.4.0 do not perform a caller authorization check for the trigger endpoint at all. Function input topics are not restricted to the function's own tenant or namespace, and registering a function does not require produce permission on its input topics. As a result, an authenticated user who is authorized to manage functions in a namespace, for example a role granted the functions permission on that namespace, can cause the Functions Worker to publish messages with caller-controlled content to a topic that the user is not authorized to produce to, including topics in other tenants. These messages are published under the identity of the Functions Worker. The issue does not require any function instance to be running or any function code to be executed. It requires that the Functions Worker's broker-client identity is itself authorized to produce to the target topic and, in Apache Pulsar 2.3.0 and later versions, to list the subscriptions of the target topic, as is the case when that identity is a superuser. The impact is on the integrity of the data in the affected topics: consumers of those topics may receive messages from a user who is not permitted to publish them. This concerns the Functions Worker REST API as called by an external, authenticated client; it does not change the security model for function code, which must be fully trusted. In fixed versions, when authorization is enabled, triggering a function additionally requires the caller to be authorized to produce to the selected input topic before any message is published. This issue affects Apache Pulsar versions from 2.0.0-rc1-incubating before 4.0.14 and from 4.1.0 before 4.2.5. - 4.0.x version users should upgrade to at least 4.0.14. - 4.1.x and 4.2.x version users should upgrade to at least 4.2.5. Users operating versions prior to those listed above should upgrade to the aforementioned patched versions or newer versions. The currently supported Apache Pulsar release lines are 4.0.x and 5.0.x. The supported versions schedule is available at https://pulsar.apache.org/contribute/release-policy/. Users of Apache Pulsar 2.4.0 and later versions with authorization enabled who cannot upgrade immediately can limit the permission to manage functions to trusted roles. Users of versions before 2.4.0 should restrict access to the Functions Worker REST API to trusted callers, because in these versions the trigger endpoint does not check the caller's permission to manage functions. --- _Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_