EUVD-2026-82584
GHSA-qhc8-w2rv-6x36
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessReach MCR endpoint over network
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DeliverySubstitute attacker-controlled key/identifier
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ExploitBypass authorization check (CWE-639)
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ExecutionAccess cross-tenant registry resource
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ImpactElevate privileges (scope change)
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Object-level authorization, IDOR prevention
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| Exploitation Conditions | No special conditions - remote unauthenticated exploitation over the network against Microsoft Container Registry (CVSS PR:N/UI:N/AC:L), requiring only that the attacker supply a manipulated user-controlled key/identifier to reference resources they should not be authorized to access. The primary limiting factor is that MCR is a Microsoft-operated cloud service: the attack surface is the hosted registry endpoint (not customer-deployed software), so remediation is applied server-side by Microsoft rather than by consumers, and the specific vulnerable feature/endpoint is not disclosed in the MSRC advisory. |
| Impact | The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N) is maximally severe and I independently confirm it computes to a full 10.0 - network-reachable, no authentication, no user interaction, low complexity, with a scope change and high confidentiality plus integrity impact. This is a genuine worst-case authorization-bypass (CWE-639, IDOR/BOLA) against Microsoft Container Registry, a heavily relied-upon cloud service. However, several real-world-risk signals are ABSENT rather than negative: no EPSS score, no CISA KEV listing, and no public POC were provided. Critically, MCR is a Microsoft-hosted cloud service, so this class of flaw is remediated server-side by the vendor - there is no customer patch, version bump, or deployment action, which sharply reduces sustained real-world risk for end users compared to a self-hosted product with the same score. The MSRC advisory is the only source and gives no root-cause detail. Net: the raw score is a true 10.0 and warrants attention, but the absence of exploitation evidence combined with vendor-managed remediation means the practical residual risk to consumers is likely already mitigated rather than an active emergency. Verify current status directly with the MSRC update guide. |
| Exploit ScenarioDerived | A remote, unauthenticated attacker manipulates a user-controlled key/identifier in a request to Microsoft Container Registry so that authorization checks reference an object the attacker should not control, letting them access or act on another tenant's registry resources and elevate privileges over the network. No public exploit code has been identified, and the sparse MSRC advisory does not disclose the exact parameter or endpoint. Given AC:L and PR:N, a working exploit would require no special preconditions or credentials once the vulnerable identifier is known. |
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Alert meAnalysisAIv1 – Sep 17, 2026
Authorization bypass in Microsoft Container Registry (MCR) lets an unauthenticated remote attacker supply a manipulated, user-controlled key to reference registry resources they are not authorized to access, producing high confidentiality and integrity impact with a scope change; the assessed CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N) independently computes to a maximum 10.0. Because MCR is a Microsoft-operated cloud service, every tenant and consumer that pulls images, charts, or artifacts from mcr.microsoft.com is potentially exposed through the hosted endpoint rather than through any customer-deployed software. No public exploit code has been identified at time of analysis and the CVE is not listed in CISA KEV, but the unauthenticated, low-complexity, network-reachable nature of the flaw means the exposure window is determined entirely by how quickly Microsoft remediates server-side.
RemediationAI
No vendor-released patch version is identified in the available data because this is a Microsoft-operated cloud service rather than installable software: remediation is Microsoft's responsibility and is applied server-side, so the primary action for consumers is to monitor the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69865 for Microsoft's confirmation that the authorization check has been fixed and for the window of exposure. No vendor-released patch identified at time of analysis, so there is nothing to upgrade on customer systems. In the interim, treat any credentials, service principals, managed identities, or registry tokens used against mcr.microsoft.com as potentially compromised if they were in use during the exposure window and rotate them, accepting the operational cost of re-issuing tokens and updating CI/CD secret stores. Harden the consumption path by pinning images to immutable digests instead of mutable tags and by verifying image signatures or provenance attestations before deployment, which limits the value of an artifact swap but adds signing infrastructure and can break pipelines that rely on floating tags. Restrict egress from build and runtime environments to a curated allowlist of known-good registry endpoints and mirror approved artifacts into a private registry, which reduces the attack surface reachable from your network at the cost of additional storage and a synchronization process that must itself be trusted. Audit registry pull logs, CI job histories, and deployment records for unexpected repositories, namespaces, or digests fetched during the exposure window and investigate any anomalous access. Because the specific vulnerable feature and endpoint are undisclosed, no targeted feature-disable workaround can be recommended without risk of breaking legitimate pulls.
Affected VersionsENISA
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Technical ContextAI · show details
The root cause class is CWE-639 (Authorization Bypass Through User-Controlled Key), a broken access control pattern in which an application accepts an object identifier supplied by the caller and resolves it directly into a lookup or storage operation without verifying that the caller is entitled to that object. In a container registry context, those keys are the namespace, repository, tag, digest, and blob/upload identifiers used by the OCI Distribution API; if the service trusts a caller-controlled key when authorizing a pull, manifest fetch, or blob access, an attacker can enumerate or retrieve content belonging to other publishers and, given the assessed high integrity impact, potentially substitute or overwrite artifacts. The scope change (S:C) indicates the flaw lets an attacker affect resources beyond the vulnerable component's own security authority, consistent with cross-repository or cross-tenant reach within the shared registry. The vector contains PR:N and UI:N, so exploitation is unauthenticated and requires no user interaction, and AC:L means no race condition or unusual preconditions are needed - only a manipulated key value. Notably, the affected system is a Microsoft-hosted service with no customer-deployed component, so there are no CPE strings to enumerate and the specific vulnerable endpoint or feature is not disclosed in the MSRC advisory. Microsoft published the issue through its own Security Response Center advisory (secure@microsoft.com); no CVE record was available from NVD at the time of this synthesis, so the MSRC update guide remains the authoritative source.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Unauthenticated network IDOR (user-controlled key) crossing an authorization boundary yields PR:N/AC:L and S:C with high confidentiality/integrity; no availability impact indicated, matching the vendor's 10.0.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
DescriptionCVE.org
Authorization bypass through user-controlled key in Microsoft Container Registry allows an unauthorized attacker to elevate privileges over a network.
Executive ViewAI
A critical authorization bypass in the Microsoft Container Registry (mcr.microsoft.com) allows an unauthenticated remote attacker to reference registry resources they are not permitted to access, with the assessed CVSS 3.1 vector computing to a maximum 10.0. Because MCR is a Microsoft-operated service, the exposure is not confined to software we deploy - it affects every team, pipeline, and product that pulls images, charts, or artifacts from this registry, and therefore carries direct supply-chain integrity implications for our build and deployment estate. Leadership should note that remediation rests entirely with Microsoft server-side, so our exposure window is governed by their response time rather than our own patch cycle.
No vendor-released patch identified at time of analysis. Interim mitigations: enforce pull-by-immutable-digest rather than mutable tags; require signature and provenance verification for all artifacts pulled from mcr.microsoft.com; mirror critical base images into a controlled internal registry and restrict build-infrastructure egress to approved registry endpoints; monitor registry pull activity for anomalous or unauthorized resource references; rotate registry credentials and tokens as a precaution; and escalate to Microsoft for a written server-side remediation status and timeline.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
Exploit-DB