`CVE-2026-24281` Apache ZooKeeper

Affected software	Apache ZooKeeper
Severity	7.4 High CVSS 3.1 3 scores
Fixed in	`3.8.6`, `3.9.5`
Weakness	CWE-295
Published	7 Mar 2026
Updated	13 Nov 2026

Description

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 servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.

CWE-350CWE-297

Exploitation status

No public exploit

No exploit has been reported in the sources we check.

CISA KEV not listed
VulnCheck KEV not listed
CISA Vulnrichment exploitation: none
Indexed PoC none indexed
EPSS 0.69% chance in 30 days

Waratek protection

Mitigation candidate

A kind of vulnerability Waratek's rules address, with exploit code published or exploitation reported. No rule exists and none is planned yet. The decision below says what we found to build a rule from.

Protection none
Action feasible
Review human Researcher
Record active

Decided by	A researcher's recorded decision for this specific CVE
Finding	A researcher set this CVE's status to Mitigation candidate.

Decided by

A researcher's recorded decision for this specific CVE

Finding

A researcher set this CVE's status to Mitigation candidate.

Waratek research note

written 2026-11-13

Written by a Waratek engineer who reviewed this CVE. Their decision sets the status above, ahead of every automated rule except a withdrawal.

No existing ARMR rule covers this.

CVE-2026-24308 - most likely this commit https://github.com/apache/zookeeper/commit/06996fe213fb2f5e02954ebaa9e3a9c61aa964ac
CVE-2026-24281 - likely the same commit, per this changeset https://github.com/apache/zookeeper/compare/release-3.8.5...release-3.8.6 - the changeset for the newer version is much bigger

CVSS

7.4 HIGH v3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N 3 metrics

We show the highest score from the newest CVSS version. Scores from different versions can't be compared, and the first score listed is sometimes a 0.0 placeholder.

Version Score Band Vector Assigner Type

CVSS 3.1 7.4 HIGH CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N NVD Primary published

CVSS 3.1 7.4 HIGH CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N redhat-SADP Secondary

CVSS 3.1 5.9 MEDIUM CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N CISA-ADP Secondary

Version	Score	Band	Vector	Assigner	Type
CVSS 3.1	7.4	HIGH	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`	NVD	Primary	published
CVSS 3.1	7.4	HIGH	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`	redhat-SADP	Secondary
CVSS 3.1	5.9	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N`	CISA-ADP	Secondary

Affected software and releases

Oracle advisories

Advisory	Type	Quarter	Products Oracle names in its risk matrix
Oracle Critical Patch Update July 2026 ↗	CPU	2026-Q3	Oracle GoldenGate / Security (Apache ZooKeeper) (19.1.0.0.0-19.1.0.0.15)
Oracle Critical Security Patch Update May 2026 ↗	CSPU	2026-Q2	Oracle Communications / Core (Apache ZooKeeper) (6.1.1-7.0.0)

Advisory

Type

Quarter

Products Oracle names in its risk matrix

Oracle Critical Patch Update July 2026 ↗

CPU

2026-Q3

Oracle GoldenGate / Security (Apache ZooKeeper) (19.1.0.0.0-19.1.0.0.15)

Oracle Critical Security Patch Update May 2026 ↗

CSPU

2026-Q2

Oracle Communications / Core (Apache ZooKeeper) (6.1.1-7.0.0)

Oracle components and versions

Family	Component	Versions, as Oracle lists them	Read as
Oracle Communications	Core (Apache ZooKeeper)	6.1.1-7.0.0
Oracle GoldenGate	Security (Apache ZooKeeper)	19.1.0.0.0-19.1.0.0.15

Family

Component

Versions, as Oracle lists them

Read as

Oracle Communications

Core (Apache ZooKeeper)

6.1.1-7.0.0

Oracle GoldenGate

Security (Apache ZooKeeper)

19.1.0.0.0-19.1.0.0.15

Maven packages

Affected and fixed versions, from OSV.dev

Package Introduced Fixed Last affected

org.apache.zookeeper:zookeeper 3.8.0 3.8.6 unbounded

org.apache.zookeeper:zookeeper 3.9.0 3.9.5 unbounded

Package	Introduced	Fixed	Last affected
`org.apache.zookeeper:zookeeper`	3.8.0	`3.8.6`	unbounded
`org.apache.zookeeper:zookeeper`	3.9.0	`3.9.5`	unbounded

Products and versions

2 products, 4 version entries

Source	Vendor	Product	Scheme	Affected versions
nvd	apache	zookeeper	generic	≥ 3.8.0 and ＜ 3.8.6 · ≥ 3.9.0 and ＜ 3.9.5
osv	org.apache.zookeeper	zookeeper	generic	≥ 3.8.0 and ＜ 3.8.6 · ≥ 3.9.0 and ＜ 3.9.5

Source

Vendor

Product

Scheme

Affected versions

nvd

apache

zookeeper

generic

≥ 3.8.0 and ＜ 3.8.6 · ≥ 3.9.0 and ＜ 3.9.5

osv

org.apache.zookeeper

zookeeper

generic

≥ 3.8.0 and ＜ 3.8.6 · ≥ 3.9.0 and ＜ 3.9.5

References

URL	Tags
https://github.com/apache/zookeeper/commit/66c4efecdda1302d9cfb3af9eedb122b74452bf3	WEB
https://github.com/apache/zookeeper	PACKAGE
https://issues.apache.org/jira/browse/ZOOKEEPER-4986	WEB
https://lists.apache.org/thread/088ddsbrzhd5lxzbqf5n24yg0mwh9jt2	WEB
http://www.openwall.com/lists/oss-security/2026/03/07/4	WEB
https://access.redhat.com/errata/RHSA-2026:10184
https://access.redhat.com/errata/RHSA-2026:14272
https://access.redhat.com/errata/RHSA-2026:14276
https://access.redhat.com/errata/RHSA-2026:34608
https://access.redhat.com/errata/RHSA-2026:8509

URL

Timeline

Published	2026-03-07	By the CVE Program.
NVD record modified	2026-07-15	NVD's own last-modified date for this record.
Classification created	2026-11-13	First commit adding this CVE's research note.
Last VRT activity	2026-11-13	Most recent commit touching this CVE's classification, patch or rule file.

Published

2026-03-07

By the CVE Program.

NVD record modified

2026-07-15

NVD's own last-modified date for this record.

Classification created

2026-11-13

First commit adding this CVE's research note.

Last VRT activity

2026-11-13

Most recent commit touching this CVE's classification, patch or rule file.

How VRT decided (4 of 24 rules ran)

4 of 24 rules ran. The rest didn't run because an earlier rule had already settled the CVE.

# Rule Outcome Status Detail

identity: Does this identifier describe a vulnerability at all? the first rule that matches decides

1 rejected no match CVE Program withdrawal of this identifier

scope: Is it a vulnerability Waratek protects? the first rule that matches decides

2 armr-patch-file no match An ARMR patch file on disk for this CVE

3 armr-secure-rule-file no match An ARMR security-rule template on disk for this CVE

4 manual-classification decided it matched Mitigation candidate A researcher set this CVE's status to Mitigation candidate.

5 manual classification not reached Manual classification of this CVE in the legacy dataset

6 non-java-upstream not reached A root cause in non-Java code: an OS kernel, a C library, or a bundled runtime

7 oracle-component not reached The defect being in a component of a tracked product the agent does not reach: JavaFX, the Java SE installer, the JInitiator browser plug-in, the native WebLogic proxy plug-in, or a native part of Oracle Application Server or Collaboration Suite (HTTP Server, Web Cache, Internet Directory, mail and calendar servers). Oracle gives these no CPE of their own and names them only in the description.

8 java-client-side not reached Oracle's own risk-matrix note saying the CVE is reached only through untrusted code in the Java sandbox (applets, Web Start) or only through a client installation of Java, so a server running its own trusted code is not exposed

9 osv-maven not reached An OSV.dev record of this CVE affecting a package published to Maven Central. When every such package is one business applications do not use (Minecraft mods and launchers, Fastjson) and no tracked product is named by CPE, it settles the CVE as Outside Waratek scope instead

10 cna-maven-package not reached An affected Maven artifact named by the CNA itself

11 known-cpe-product not reached An NVD CPE naming a product ARMR tracks

12 cna-cpe-product not reached A CPE the CNA published naming a tracked product. Oracle publishes these on advisory day, months before NVD.

13 oracle-advisory-family not reached A tracked product family named in Oracle's own risk matrix. CPE cannot carry a suite name, only a module.

14 cna-named-product not reached A tracked product named in words by the CVE's own CNA, on a record with no CPE yet. Apache and Eclipse publish these on advisory day, before NVD adds CPE data.

15 non-deployable-product not reached The only affected product being a sealed appliance image, where Java runs but no -javaagent can be attached

16 unmatched-product not reached No tracked product matched above, and none present at all

disposition: What do we do about one that is? every rule runs

17 patch-hint not reached A reference pointing at the upstream fix: a commit, a PR, a Red Hat bug

18 open-source-maven not reached The affected package being open source on Maven, so the fix can be read

19 poc-derivable not reached An indexed exploit clearing the evidence bar to reverse-engineer, where there is no source to read

20 no-exploit not reached Nothing to build a rule from yet: no published exploit, no CISA record of exploitation and no source-level change to read

21 secure-rule-match not reached A vulnerability class already blocked by an ARMR security rule

22 exploited-no-fix-or-poc not reached Somebody exploiting this CVE (a CISA or VulnCheck KEV listing, or a CISA verdict of active exploitation), with no fix, source code or PoC to build a rule from

23 below-action-threshold not reached Medium or Low severity, no CISA or VulnCheck KEV listing, no PoC clearing the evidence bar, no CISA verdict, no Oracle advisory

24 no-exploit-published not reached Exploit code for this candidate, published in a reviewed catalogue or a GitHub repository with 5 or more stars, or in use per CISA or VulnCheck; not only a CISA verdict, a forecast, or nothing at all

NVD ↗ · CVE.org ↗