Quick answers
- Is CVE-2026-100300 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-100300 being exploited in the wild.
- How severe is CVE-2026-100300?
- Informational severity, published 4 November 2026.
- Which products and versions are affected?
- Apache Zookeeper up to 3.9.6.
- Is there a fix for CVE-2026-100300?
- Yes: fixed in ZooKeeper 3.8.8, 3.9.7. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-100300 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-100300?
- Check whether you run Apache Zookeeper at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: ZooKeeper 3.8.8, 3.9.7
Technical details
Improper exception handling in ZooKeeper's quota subsystem allows an attacker with write access to the /zookeeper/quota subtree to trigger a crash in the request-processing thread. On default deployments where this subtree is world-writable, this requires no authentication. The crash results in permanent corruption of the data directory, preventing the server from booting.
Affected products
- Apache ZooKeeper up to 3.9.6
Timeline
- 2026-11-04: disclosed