CVE-2026-105926: The Pulsar broker serves two schema commands on its binary protocol: GetSchema, which returns the schema registered for a topic, and GetOrCreateSchema, which re

The Pulsar broker serves two schema commands on its binary protocol: GetSchema, which returns the schema registered for a topic, and GetOrCreateSchema, which re

The Pulsar broker serves two schema commands on its binary protocol: GetSchema, which returns the schema registered for a topic, and GetOrCreateSchema, which registers a new schema version for an existing topic. The broker handled both commands after checking only that the client connection was authenticated. Unlike the broker's other topic commands, such as those for creating producers and consumers or for looking up topics, these two commands did not check whether the authenticated client was authorized for the target topic. The Pulsar REST API endpoints for schemas were not affected. An authenticated client without any permission on the target topic, namespace or tenant could use these commands to: - read the schema registered for a topic in another namespace or tenant, disclosing the schema definition such as record field names and types. Message payloads are not disclosed. - register a new schema version on an existing topic in another namespace or tenant. The topic's schema compatibility and schema auto-update policies still apply. The issue does not allow message data to be read or modified, but a registered schema version can cause legitimate producers and consumers of th

Description from the National Vulnerability Database, published by security@apache.org

What it means for a small business

Apache Pulsar runs on web servers, so this is mostly your hosting company's to fix. On shared hosting you can't patch it yourself, but you can ask.

Ask your host whether your server runs it, whether it's updated, and on what date. A good host answers that in a day.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.41%, higher than 34% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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