Apache ZooKeeper: Missing Authorization (CVE-2026-79993)
Published Last modified Sources: Red Hat, BSI, CVE.org, OSV
What is affected, what to do
A flaw was found in Apache ZooKeeper. The deleteContainer opcode is processed without verifying Access Control List (ACL) permissions.
Update zookeeper to version 3.8.7.
- Affected
- Apache ZooKeeper
lte 3.9.0..3.9.5 - Apache ZooKeeper
lte 3.8.0..3.8.6
- Apache ZooKeeper
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Metrics
7.5
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: Vendor (CNA), CVSS v3
7.5
CVSS v3
Severity High on the scale from 0 to 10.
Source: Red Hat, BSI, CVE.org, OSV
0.6 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 49.0
Show all metrics
- Severity
- High
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 82.82 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 7.5 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 7.5
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 0.6 %
- Low — model estimates < 1% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 49.0
- High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
- CISA assessment (SSVC)
- Exploitation: none known · automatable · Technical impact: partial
- Source: CISA Vulnrichment, as of 17 September 2026
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-862
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
A flaw was found in Apache ZooKeeper. The deleteContainer opcode is processed without verifying Access Control List (ACL) permissions. A remote, unauthenticated attacker with network access to the ZooKeeper client port can delete any empty persistent znode, including container and TTL nodes. This can lead to data integrity issues or denial of service.
Source: redhat_csaf, BSI WID Portal, BSI CSAF, cvelistv5, OSV (Open Source Vulnerabilities), NVD (NIST)
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Apache Software Foundation | Apache ZooKeeper |
|
|
| apache | zookeeper |
|
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| IBM | SPSS |
|
|
Vendors and products
Weakness classes (CWE)
CWE-862Missing Authorization
Class
The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
Entry at MITRE CWE-862
References & sources
- lists.apache.orgthread/9cw3rmrzhqpct26v8j18fy41bghlq8y5Vendor advisory
- openwall.comlists/oss-security/2026/09/15/5
- NVD (NIST)vuln/detail/CVE-2026-79993web
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Initial analysis by NVDNVD
Newly listed as affected:- Apache Software Foundation Apache ZooKeeper (3.8.0 – before 3.8.7; 3.9.0 – before 3.9.6)
Show 3 original changes
Individual changes of this event as published by NVD Type Action Before After Product configuration added —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) 3.9.6Reference type added —Apache Software Foundation: https://lists.apache.org/thread/9cw3rmrzhqpct26v8j18fy41bghlq8y5 Types: Mailing List, Vendor AdvisoryReference type added —CVE: http://www.openwall.com/lists/oss-security/2026/09/15/5 Types: Mailing ListSource identifier: nvd@nist.gov
Record modifiedCISA ADP
CVSS V3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CISA assessment (SSVC): exploitation: none known, automatable: yes
Show 2 original changes
Individual changes of this event as published by NVD Type Action Before After CVSS added —AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NSSVC assessment added —{"id":"CVE-2026-79993","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-17T19:15:43.099911Z"}Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Record modifiedCVE Program
New references:Show the original change
Individual changes of this event as published by NVD Type Action Before After Reference added —http://www.openwall.com/lists/oss-security/2026/09/15/5Source identifier: af854a3a-2127-422b-91ae-364da2661108
ReceivedApache
Weakness type: CWE-862
Description added or changed
Show 4 original changes
Individual changes of this event as published by NVD Type Action Before After Description added —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 restrictions on the znode or its parent. This opcode is considered internal-only and the official client doesn't have API for it, but a client that can open a plain TCP session on the ZooKeeper client port (2181 by default) - with NO authentication and NO ACL permissions - can delete any empty persistent znode (including regular persistent nodes, container nodes, and TTL nodes) by issuing the raw protocol OpCode deleteContainer (20). The deleteContainer request path completely skips both the session check and the DELETE ACL check that are enforced by the regular delete (OpCode 2) path. This is an authorization bypass / ACL enforcement bug. This issue affects Apache ZooKeeper: from 3.9.0 through 3.9.5, from 3.8.0 through 3.8.6. Users are recommended to upgrade to version 3.9.6 or 3.8.7, which fixes the issue.Weakness type (CWE) added —CWE-862Affected versions (publisher) added —New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/79xxx/CVE-2026-79993.json">CVE-2026-79993</a>Reference added —https://lists.apache.org/thread/9cw3rmrzhqpct26v8j18fy41bghlq8y5Source identifier: security@apache.org
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