Severity:
CVSS 4.0: 4.9 (medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N
Affected versions:
- Apache Pulsar 2.0.0-rc1-incubating before 4.0.14
- Apache Pulsar 4.1.0 before 4.2.5
Description:
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.
Credit:
Omar Mousa (finder)
References:
https://pulsar.apache.org/security/CVE-2026-105935/
https://pulsar.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-105935
