Apache Zookeeper vulnerabilities

16 CVEs affecting Apache Zookeeper, 0 known to be exploited (CISA KEV), with EPSS scores. Latest: CVE-2026-84501, published 2026-09-16.

Highest priority

Known exploited (CISA KEV) first, then by EPSS exploit probability.

CVE-2017-5637, published 2017-10-10. High severity, CVSS 7.5. EPSS: 73.1% chance of exploitation in the next 30 days. Two four letter word commands "wchp/wchc" are CPU intensive and could cause spike of CPU utilization on Apache ZooKeeper server if abused, which leads to the server unable to serve legitimate client…
CVE-2021-21295, published 2021-03-09. Medium severity, CVSS 5.9. EPSS: 18.9% chance of exploitation in the next 30 days. Netty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty…
CVE-2019-0201, published 2019-05-23. Medium severity, CVSS 5.9. EPSS: 9.7% chance of exploitation in the next 30 days. An issue is present in Apache ZooKeeper 1.0.0 to 3.4.13 and 3.5.0-alpha to 3.5.4-beta. ZooKeeper’s getACL() command doesn’t check any permission when retrieves the ACLs of the requested node and…
CVE-2018-8012, published 2018-05-21. High severity, CVSS 7.5. EPSS: 8.5% chance of exploitation in the next 30 days. No authentication/authorization is enforced when a server attempts to join a quorum in Apache ZooKeeper before 3.4.10, and 3.5.0-alpha through 3.5.3-beta. As a result an arbitrary end point could…
CVE-2016-5017, published 2016-09-21. High severity, CVSS 8.1. EPSS: 7.9% chance of exploitation in the next 30 days. Buffer overflow in the C cli shell in Apache Zookeeper before 3.4.9 and 3.5.x before 3.5.3, when using the "cmd:" batch mode syntax, allows attackers to have unspecified impact via a long command…
CVE-2023-44981, published 2023-10-11. Critical severity, CVSS 9.1. EPSS: 2.2% chance of exploitation in the next 30 days. Authorization Bypass Through User-Controlled Key vulnerability in Apache ZooKeeper. If SASL Quorum Peer authentication is enabled in ZooKeeper (quorum.auth.enableSasl=true), the authorization is done…
CVE-2026-24308, published 2026-03-07. High severity, CVSS 7.5. EPSS: 1.2% chance of exploitation in the next 30 days. Improper handling of configuration values in ZKConfig in Apache ZooKeeper 3.8.5 and 3.9.4 on all platforms allows an attacker to expose sensitive information stored in client configuration in the…
CVE-2024-51504, published 2024-11-07. Critical severity, CVSS 9.1. EPSS: 0.9% chance of exploitation in the next 30 days. When using IPAuthenticationProvider in ZooKeeper Admin Server there is a possibility of Authentication Bypass by Spoofing -- this only impacts IP based authentication implemented in ZooKeeper Admin…
CVE-2026-84501, published 2026-09-16. Medium severity, CVSS 5.3. EPSS: 0.7% chance of exploitation in the next 30 days. An unauthenticated attacker can inject arbitrary fake log lines into Apache ZooKeeper's operational log by sending a crafted add_auth("ensemble", ...) request containing newline characters (\n). When…
CVE-2026-84439, published 2026-09-16. Medium severity, CVSS 5.3. EPSS: 0.7% chance of exploitation in the next 30 days. When audit logging is enabled (zookeeper.audit.enable=true), an unauthenticated attacker can inject arbitrary fields into Apache ZooKeeper's audit log by sending a digest authentication request with…

Latest

CVE-2026-79993, published 2026-09-16. High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days. The `deleteContainer` opcode (0x14/20) is processed without verifying the caller's ACL permissions, allowing any authenticated client to delete specific znodes in the data tree regardless of the ACL…
CVE-2026-59969, published 2026-09-16. High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days. Apache ZooKeeper quorum TLS fails to enforce peer hostname verification in FIPS-mode deployments. When sslQuorum=true, zookeeper.fips-mode=true, ssl.quorum.hostnameVerification=true, and…
CVE-2026-59739, published 2026-09-16. High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days. Information disclosure via SetWatches reconnect replay in Apache ZooKeeper due to missing ACL check. An attacker can discover ACL-restricted paths by registering exists-watches on non-existent paths,…
CVE-2026-24281, published 2026-03-07. High severity, CVSS 7.4. EPSS: 0.6% chance of exploitation in the next 30 days. Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper…
CVE-2025-58457, published 2025-09-24. Medium severity, CVSS 4.3. EPSS: 0.3% chance of exploitation in the next 30 days. Improper permission check in ZooKeeper AdminServer lets authorized clients to run snapshot and restore command with insufficient permissions. This issue affects Apache ZooKeeper: from 3.9.0 before…
CVE-2024-23944, published 2024-03-15. Medium severity, CVSS 5.3. EPSS: 0.2% chance of exploitation in the next 30 days. Information disclosure in persistent watchers handling in Apache ZooKeeper due to missing ACL check. It allows an attacker to monitor child znodes by attaching a persistent watcher (addWatch command)…