VulnerabilityPublished 16 Sep 2026Updated 17 Oct 2026

CVE-2026-59739: zookeeper · Information Disclosure via SetWatches Reconnect Replay

Affects zookeeperSource GCVE Database

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Mentioned vulnerabilities

CVE-2024-23944

Authoritative record:CVE-2026-59739· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade to 3.9.6 or 3.8.7 soon.

Data as of 1 Nov 2026, 22:58 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.9.6, 3.8.7

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 16 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-wrgg-c9rw-j78f

What to do

Upgrade org.apache.zookeeper/zookeeper to 3.9.6 or 3.8.7.

Affected software

Product	Affected	Fixed in
Mavenorg.apache.zookeeper/zookeeper`pkg:maven/org.apache.zookeeper/zookeeper`Other threats	Affected <3.8.7 <3.9.6	Fixed in 3.8.7 3.9.6
Ubuntu Pro 14.04 LTSzookeeper`pkg:deb/ubuntu/zookeeper?arch=source&distro=esm-infra-legacy/trusty`Other threats	Affected =3.4.5+dfsg-1 =3.4.5+dfsg-1ubuntu0.1~esm1 =3.4.5+dfsg-1ubuntu0.1~esm3	Fixed in–
Ubuntu Pro 16.04 LTSzookeeper`pkg:deb/ubuntu/zookeeper?arch=source&distro=esm-apps/xenial`Other threats	Affected 3.4.6-8 – 3.4.8-1ubuntu0.1~esm2 5 affected builds	Fixed in–
Ubuntu Pro 18.04 LTSzookeeper`pkg:deb/ubuntu/zookeeper?arch=source&distro=esm-apps/bionic`Other threats	Affected 3.4.10-2 – 3.4.13-3ubuntu0.1~esm1 4 affected builds	Fixed in–
Ubuntu 20.04 LTSzookeeper`pkg:deb/ubuntu/zookeeper?arch=source&distro=focal`Other threats	Affected 3.4.13-1 – 3.4.13-5ubuntu0.1 7 affected builds	Fixed in–
Ubuntu 22.04 LTSzookeeper`pkg:deb/ubuntu/zookeeper?arch=source&distro=jammy`Other threats	Affected 3.4.13-5ubuntu4 – 3.4.13-6ubuntu4.1 5 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Users should upgrade Apache ZooKeeper to versions 3.8.7 or 3.9.6 or later, where this vulnerability is fixed. No other mitigations are indicated in the advisory. Patch status is confirmed by the vendor advisory recommending these versions.

Description

CVE-2026-59739 is an information disclosure vulnerability in Apache ZooKeeper caused by a missing ACL check during SetWatches reconnect replay. An attacker can discover paths protected by ACLs by registering watches on non-existent paths and reconnecting after those paths are created with restricted ACLs. The vulnerability exposes the znode path but not its data. Since paths may contain sensitive information such as usernames or login IDs, this issue is potentially critical. The vulnerability affects multiple versions prior to 3.8.7 and 3.9.6. Upgrading to versions 3.8.7 or 3.9.6 resolves the issue.

Impact

The vulnerability allows an unauthenticated attacker to discover the existence of ACL-restricted znode paths in Apache ZooKeeper by exploiting the missing ACL check during watch reconnect replay. Although the data of the znodes is not disclosed, the path names themselves can leak sensitive information such as usernames or login IDs. This information disclosure can aid attackers in reconnaissance and further attacks. The CVSS score is 7.5 (High impact on confidentiality, no impact on integrity or availability).

Summary

This vulnerability arises from an incomplete fix for CVE-2024-23944 in Apache ZooKeeper. While ACL checking was added to WatchManager.triggerWatch(), the DataTree.setWatches() method, which handles SetWatches/SetWatches2 reconnect replay, still calls watcher.process(event) without ACL checks, allowing bypass. This enables an attacker to register exists-watches on non-existent paths and upon reconnection, if those paths are created with restricted ACLs, the attacker can learn the existence of these ACL-restricted paths. The vulnerability does not disclose znode data, only the path names, which may contain sensitive information. The issue affects versions before 3.8.7 and 3.9.6, including several specific older versions.

CWE-862Missing Authorization (opens in a new tab)
Class weaknessLikelihood of exploit: HighCWE Top 25 (2025): #4OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
Architecture and Design
Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries.
Architecture and Design
Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.8 (opens in a new tab)
V13.4.2 (opens in a new tab)
V7.2.2 (opens in a new tab)
Attack patterns
Exploitation of Thunderbolt Protection Flaws (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 18 Oct 2026, 04:37 UTC

WeaknessesCWE-862

Technical details

References

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