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Full vulnerability report · 2026
CVE-2026-66797High confidence

Apache CloudStack: Unauthorised comment creation and disclosure

Apache Software Foundation · Apache CloudStack

5.4MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-66797 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitycluster-backup-operator: cluster-backup-operator: Velero Restore includes cluster-scoped RBAC resources with no exclusion — tampered backup yields hub cluster-admin
24 fixed

The vendor explicitly identifies these products or versions as containing the fix.

  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:44ddf9fae94ac2f4e74c35433a612c8a0dabf531384f2974a8c4872cde0efaa1_arm64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.11
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:5291e93f95e8350e361470eec8cd6cac6e697aa712fb061bfa780981a47cb17b_ppc64le as a component of Red Hat Advanced Cluster Management for Kubernetes 2.11
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:a1af35a23b6ed7aeb297bb59d6ffa84505769c36727c6628667dddd4d87569ad_s390x as a component of Red Hat Advanced Cluster Management for Kubernetes 2.11
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:e934fad530ced942202a8e893c1ee4a931856709a46a9d711e67779cbf9d48ee_amd64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.11
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:016023aaab9f3476900a3e7bf2126875500dd171834bad8c395f42a2baae795e_ppc64le as a component of Red Hat Advanced Cluster Management for Kubernetes 2.13
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:4641f23fc762a798ea7a94e85c44fbf21f37fb8c74d93d9f39c4fe120fd8704a_arm64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.13
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:dd29bb691d5495ef504883b012248b03a4d8109000ba85dc470b0acb280aab40_s390x as a component of Red Hat Advanced Cluster Management for Kubernetes 2.13
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:f04d7d5454141691568e02f461bdca9bc58cc07f33244caf4f1caf27cd1d5866_amd64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.13
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:04fe2d4880d42890325ff697c84bd413218a9fd7f316c4dd195eb307ee2ae859_arm64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.14
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:3ffb54a51d08d77a3340914bac096cb31dc71145f681a9bcd311f1c38e4256a1_amd64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.14
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:b1b9c8a2641af71bc376784ad4ee622e116529a512e1a619a227fc8a19bd0af2_ppc64le as a component of Red Hat Advanced Cluster Management for Kubernetes 2.14
  • registry.redhat.io/rhacm2/cluster-backup-rhel9-operator@sha256:ffa6981a04f2439051744797f933da5221f7a96c46998188014e90b999a3ffd3_s390x as a component of Red Hat Advanced Cluster Management for Kubernetes 2.14
Summary
A flaw was found in the cluster-backup-operator. An attacker with write access to the backup storage location or the ability to create a Velero Backup object can inject malicious Role-Based Access Control (RBAC) resources into a backup. When this tampered backup is restored, the operator processes the malicious content, leading to a privilege escalation from backup-namespace-admin to hub cluster-admin. This allows the attacker to gain administrative control over the entire cluster.
Remediation
Before you apply this update, make sure all previously released errata that are relevant to your system are applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-63831

No EUVD known-exploited evidence

Improper access control in CloudStack's annotation functionality allows unauthorized comment creation and disclosure. The addAnnotation and listAnnotation APIs perform an ownership check when an entity's UUID is specified, but fail to honor its result correctly. This lets any authenticated user write annotations to, and disclose existing annotations/comments on, an entity they don't own by simply supplying its UUID. This issue affects Apache CloudStack: from 4.15.0.0 through 4.20.3.0 and from 4.21.0.0 through 4.22.1.0. Users are recommended to upgrade to version 4.20.3.1 or 4.22.1.1 or later, which fixes the issue.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
5.4 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

Improper access control in CloudStack's annotation functionality allows unauthorized comment creation and disclosure. The addAnnotation and listAnnotation APIs perform an ownership check when an entity's UUID is specified, but fail to honor its result correctly. This lets any authenticated user write annotations to, and disclose existing annotations/comments on, an entity they don't own by simply supplying its UUID. This issue affects Apache CloudStack: from 4.15.0.0 through 4.20.3.0 and from 4.21.0.0 through 4.22.1.0. Users are recommended to upgrade to version 4.20.3.1 or 4.22.1.1 or later, which fixes the issue.

What

Improper access control in CloudStack's annotation functionality allows unauthorized comment creation and disclosure. The addAnnotation and listAnnotation APIs perform an ownership check when an entity's UUID is specified, but fail to honor its result correctly. This lets any authenticated user write annotations to, and disclose existing annotations/comments on, an entity they don't own by simply supplying its UUID. This issue affects Apache CloudStack: from 4.15.0.0 through 4.20.3.0 and from 4.21.0.0 through 4.22.1.0. Users are recommended to upgrade to version 4.20.3.1 or 4.22.1.1 or later, which fixes the issue.

Why

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Improper access control in CloudStack's annotation functionality allows unauthorized comment creation and disclosure. The addAnnotation and listAnnotation APIs perform an ownership check when an entity's UUID is specified, but fail to honor its result correctly. This lets any authenticated user write annotations to, and disclose existing annotations/comments on, an entity they don't own by simply supplying its UUID. This issue affects Apache CloudStack: from 4.15.0.0 through 4.20.3.0 and from 4.21.0.0 through 4.22.1.0. Users are recommended to upgrade to version 4.20.3.1 or 4.22.1.1 or later, which fixes the issue.

Why

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Improper Access Control → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-284 ↗

CWE-284: Improper Access Control. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CLowConfidentiality impact: A successful attack can cause a limited loss.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkCWE-284
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-63831Official EUVD mapping

Improper access control in CloudStack's annotation functionality allows unauthorized comment creation and disclosure. The addAnnotation and listAnnotation APIs perform an ownership check when an entity's UUID is specified, but fail to honor its result correctly. This lets any authenticated user write annotations to, and disclose existing annotations/comments on, an entity they don't own by simply supplying its UUID. This issue affects Apache CloudStack: from 4.15.0.0 through 4.20.3.0 and from 4.21.0.0 through 4.22.1.0. Users are recommended to upgrade to version 4.20.3.1 or 4.22.1.1 or later, which fixes the issue.

Official EUVD record ↗
BSI · German · WID-SEC-2026-2962Apache CloudStack: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Apache CloudStack ausnutzen, um beliebigen Programmcode mit Administratorrechten auszuführen, um Informationen offenzulegen, um Dateien zu manipulieren, um einen Cross-Site Scripting Angriff durchzuführen, um Sicherheitsvorkehrungen zu umgehen und um beliebigen Programmcode auszuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260826Security Bulletin 26 Aug 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 26 Aug 2026, published on 26 August 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-030739Apache Software FoundationのCloudStackにおけるアクセス制御に関する脆弱性

CloudStackの注釈機能における不適切なアクセス制御により、認可されていないコメントの作成および情報漏洩が可能になります。addAnnotationおよびlistAnnotation APIは、エンティティのUUIDが指定された場合に所有権のチェックを実施しますが、その結果を正しく反映していません。これにより、認証済みの任意のユーザーが、対象のUUIDを指定するだけで、自分が所有していないエンティティに対して注釈を書き込み、既存の注釈やコメントを閲覧できてしまいます。この問題はApache CloudStackのバージョン4.15.0.0から4.20.3.0、および4.21.0.0から4.22.1.0に影響を与えます。ユーザーは、この問題を修正したバージョン4.20.3.1または4.22.1.1以降にアップグレードすることを推奨します。

Official advisory ↗
NCSC-NL · Dutch · NCSC-2026-0332Kwetsbaarheden verholpen in Apache CloudStack

Two vulnerabilities affect Red Hat Advanced Cluster Management for Kubernetes and Apache CloudStack, enabling privilege escalation via malicious RBAC injection and improper access control in annotation APIs, respectively.

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Apache CloudStack: 4.16.0.0 ≤ 4.20.3.0, 4.21.0.0 ≤ 4.22.1.0
Fixed
Action
Before you apply this update, make sure all previously released errata that are relevant to your system are applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 21 Aug 2026 · Last source change 21 Aug 2026, 19:45 UTC · CWE-284 · Improper Access Control

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-23
European sourceENISA EUVD · EUVD-2026-63831
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed from no authoritative guidance recorded to vendor advisory.
    Before
    no authoritative guidance recorded
    After
    vendor advisory
    security@apache.org ↗
  2. SeveritySeverity changed from Unknown to Medium.
    Before
    Unknown
    After
    Medium
    CISA ADP ↗
  3. CVSS scoreCVSS score changed from not recorded to 5.4 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N).
    Before
    not recorded
    After
    5.4 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N)
    CISA ADP ↗
  4. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2026-63831↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-66797 · cve.blacktree.nl