Is CVE-2026-100235 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-100235 being exploited in the wild.

How severe is CVE-2026-100235?

Informational severity, published 4 November 2026.

Which products and versions are affected?

Apache Zookeeper up to and including 3.9.6.

Is there a fix for CVE-2026-100235?

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-2026-100235 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-100235?

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.

CVE-2026-100235: Apache ZooKeeper setACL time-of-check time-of-use race condition

CVE-2026-100235 · Severity: info · Published 2026-11-04

Apache ZooKeeper, which manages configuration and coordination for distributed systems, has a race condition in its access control list (ACL) revocation process. An attacker who currently has permission to modify data can exploit a timing window to continue making changes even after their access is revoked, or to re-grant themselves full permissions, defeating the intended access control. This is particularly dangerous during migrations from open to restricted access policies.

Technologies: Apache Zookeeper. Vendors: Apache.

Quick answers

Is CVE-2026-100235 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-100235 being exploited in the wild.
How severe is CVE-2026-100235?: Informational severity, published 4 November 2026.
Which products and versions are affected?: Apache Zookeeper up to and including 3.9.6.
Is there a fix for CVE-2026-100235?: 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-2026-100235 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-100235?: 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

A TOCTOU race condition exists in setACL request handling: the ACL change is not immediately published to the server's outstanding change record, allowing requests authorized under the old ACL to be applied after the ACL revision takes effect. An authenticated or previously-authorized client can exploit this window to perform privileged operations through and after permission revocation. A fix is available in versions 3.8.8 and 3.9.7.

Affected products

Apache ZooKeeper up to and including 3.9.6

Timeline

2026-11-04: disclosed

References

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