CVE-2026-59969
Apache ZooKeeper: Improper validation of certificate with host mismatch in FIPS mode
Description
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 ssl.quorum.clientHostnameVerification=true are enabled, the Java SSLSocket quorum path accepts a CA-trusted peer certificate whose SAN does not match the connected host. A malicious or misissued peer certificate can therefore join quorum traffic, participate in leader election, and enter replication flows. Users are recommended to upgrade to version 3.8.7 or 3.9.6, which fixes the issue.
INFO
Published Date :
Sept. 16, 2026, 10:16 a.m.
Last Modified :
Sept. 18, 2026, 2:31 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Upgrade to Apache ZooKeeper version 3.8.7 or 3.9.6.
- Verify TLS configurations for quorum peers.
- Ensure hostname verification is correctly enforced.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-59969.
| URL | Resource |
|---|---|
| https://lists.apache.org/thread/qf9kwsgtgbgtvwls6f41281846xg0rss | Mailing List Vendor Advisory |
| http://www.openwall.com/lists/oss-security/2026/09/15/4 | Mailing List Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-59969 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-59969
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-59969 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-59969 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Sep. 18, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:apache:zookeeper:*:*:*:*:*:*:*:* versions from (including) 3.8.0 up to (excluding) 3.8.7 *cpe:2.3:a:apache:zookeeper:*:*:*:*:*:*:*:* versions from (including) 3.9.0 up to (excluding) 3.9.6 Added Reference Type Apache Software Foundation: https://lists.apache.org/thread/qf9kwsgtgbgtvwls6f41281846xg0rss Types: Mailing List, Vendor Advisory Added Reference Type CVE: http://www.openwall.com/lists/oss-security/2026/09/15/4 Types: Mailing List, Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 17, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Added SSVC {'id': 'CVE-2026-59969', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-09-17T19:16:38.006304Z'} -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Sep. 16, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/09/15/4 -
New CVE Received by [email protected]
Sep. 16, 2026
Action Type Old Value New Value Added Description 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 ssl.quorum.clientHostnameVerification=true are enabled, the Java SSLSocket quorum path accepts a CA-trusted peer certificate whose SAN does not match the connected host. A malicious or misissued peer certificate can therefore join quorum traffic, participate in leader election, and enter replication flows. Users are recommended to upgrade to version 3.8.7 or 3.9.6, which fixes the issue. Added CWE CWE-297 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/59xxx/CVE-2026-59969.json">CVE-2026-59969</a> Added Reference https://lists.apache.org/thread/qf9kwsgtgbgtvwls6f41281846xg0rss