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Azure Kubernetes Service CVE-2026-50516

| EUVDEUVD-2026-56778 CRITICAL
Missing Authentication for Critical Function (CWE-306)
2026-08-11 secure@microsoft.com GHSA-pq49-h7qm-894f
9.4
CVSS 3.1 · Vendor: microsoft
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Reach exposed AKS endpoint over network
  2. Delivery
    Invoke critical function lacking auth check
  3. Exploit
    Bypass missing authentication
  4. Execution
    Obtain elevated cluster privileges
  5. Impact
    Access secrets and alter resources

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication required for critical functions
MITRE ATT&CK

1 technique across 1 tactic: Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Per the CVSS vector (AV:N/AC:L/PR:N/UI:N), no special conditions are required beyond network reachability - remote unauthenticated exploitation against the exposed AKS function, with no authentication, no user interaction, and low attack complexity. The concrete prerequisite is network-layer access to the vulnerable AKS endpoint that exposes the critical function; the primary limiting factor is therefore reachability - clusters deployed as private clusters or behind API server authorized IP ranges, or otherwise not exposing the affected endpoint to the attacker's network, substantially constrain exploitation. The exact affected function/feature is not detailed in the public description (MSRC coordinated disclosure), so the specific configuration surface should be confirmed against the vendor advisory.

Impact

The signals are largely aligned toward high real-world risk: the CVSS 3.1 base of 9.4 is driven by AV:N (network), AC:L (low complexity), PR:N (no privileges) and UI:N (no user interaction), meaning an attacker needs only network reach to the exposed function, and impact is High confidentiality, High integrity, Low availability. That combination - remote, unauthenticated, low-complexity privilege elevation - is the profile defenders most fear in a shared cloud platform, and given how widely AKS underpins production workloads, even a mid-sized municipal IT team running a handful of AKS clusters should treat this as urgent rather than routine. Countervailing factors temper the urgency somewhat: there is no EPSS score provided in the input, no public POC identified, and the CVE is not listed in CISA KEV, so there is no evidence of active or automated exploitation yet. Scope is Unchanged (S:U), which slightly limits blast radius versus a scope-changing container-escape. One data caveat worth flagging: no EPSS value was supplied, so exploitation probability cannot be quantified here, and the exact vulnerable function is not described publicly (typical for MSRC coordinated disclosure), so verify specifics against the Microsoft advisory. Overall this is a genuine high priority, but the risk is currently 'exposed and severe by design' rather than 'confirmed under attack.'

Exploit ScenarioDerived

An attacker with network access to an exposed AKS endpoint sends requests directly to a privileged function that performs no authentication check, and because no credentials or user interaction are needed (PR:N/UI:N), the request is honored as if authorized, granting elevated privileges within the cluster. From there the attacker can read sensitive workload secrets and tamper with cluster resources (C:H/I:H). No public POC is identified at time of analysis, so exploitation would currently require independent discovery of the specific vulnerable function.

Monitor Track and reassess. Why: Vendor states no customer action required.
No patch listed yet 0.8% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 11, 2026

Privilege elevation in Microsoft Azure Kubernetes Service (AKS) lets a network-based, unauthenticated attacker gain elevated privileges by reaching a critical function that lacks an authentication check (CWE-306). Microsoft rates it 9.4 (Critical) with an AV:N/AC:L/PR:N/UI:N vector, indicating trivial remote reachability and no user interaction, though scope is unchanged. There is no public exploit identified at time of analysis and it is not on CISA KEV, but the missing-auth root cause and high confidentiality/integrity impact make it a high-priority cloud-platform issue.

RemediationAI

Because AKS is a Microsoft-managed service, the primary fix is delivered server-side by Microsoft; consult the vendor advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50516 to confirm whether any customer action (such as upgrading cluster node images or the Kubernetes control-plane version, or applying a specific AKS release) is required, since no exact fixed version was included in the source data - treat this as 'patch available per vendor advisory' rather than an independently confirmed version number. Operationally, ensure clusters are on a supported, auto-upgraded AKS channel so the fix lands automatically, and restrict network exposure of control-plane and node endpoints by enabling private clusters or API server authorized IP ranges so the critical function is not reachable from arbitrary networks (trade-off: authorized IP ranges and private clusters can break CI/CD runners or admin tooling that connect from unlisted addresses, so update allowlists first). Additionally enforce Kubernetes RBAC least privilege and audit for anomalous privileged API calls as detective compensating controls; these do not replace the vendor fix but reduce reachability and improve detection while you validate patch status.

Affected VersionsENISA

Azure Kubernetes Service - (version not specified)

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The affected component is Azure Kubernetes Service, Microsoft's managed Kubernetes control-plane and worker-node offering on Azure. The root cause is CWE-306 (Missing Authentication for Critical Function): a security-sensitive operation - one that in a hardened design would require authenticating and authorizing the caller - is exposed without verifying the requester's identity. In a Kubernetes context, critical functions typically include control-plane API endpoints, node bootstrap/registration, kubelet or admission interfaces, and identity/token issuance; when any such function is reachable without authentication, an attacker who can send network requests to it can invoke privileged behavior directly. Because AKS is a managed service, the vulnerable surface is Microsoft-operated infrastructure rather than customer-patched binaries, so remediation is delivered service-side. The EUVD record lists the affected product simply as 'Azure Kubernetes Service' without a discrete version string, consistent with a continuously-updated cloud service rather than a versioned on-prem package; no CPE was provided in the input.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 9.4 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
ENISA EUVD HIGH
vuln.today AI 9.4 CRITICAL

Missing authentication on a network-reachable critical function gives AV:N/AC:L/PR:N/UI:N; privilege elevation yields high confidentiality and integrity with limited availability impact, scope unchanged.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

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

DescriptionCVE.org

Missing authentication for critical function in Microsoft Azure Kubernetes Service allows an unauthorized attacker to elevate privileges over a network.

Executive ViewAI

Why It Matters

Microsoft Azure Kubernetes Service (AKS) customers face immediate remote privilege escalation risk-no public exploit identified at time of analysis, but a missing authentication check creates trivial remote reachability with no user interaction required. An unauthenticated attacker with network access can gain elevated privileges within AKS clusters, compromising container orchestration, data confidentiality, and platform integrity. All AKS deployments require immediate network controls pending patch availability.

Business Impact: Severe
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: implement network access controls (NSGs, firewalls) to restrict connectivity to AKS API endpoints and limit exposure to trusted networks only; enforce Pod Security Policies and RBAC restrictions to minimize privilege escalation paths within clusters; enable comprehensive audit logging of authentication and authorization events; implement intrusion detection rules targeting privilege escalation behavior; consider isolating or reducing workload criticality on AKS clusters until patch availability; regularly review cluster access logs and authentication attempts for suspicious activity patterns.

Threat Intelligence Overview

EPSS Score
0.8%
Top 47% exploitable
Prevalence
High
AKS is a widely deployed managed Kubernetes platform across enterprise Azure environments
Threat Intel
2
1 sources
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
Service Type
Hosted
Vendor-managed, no client patch needed
Data Quality
8 sources
Confidence: High

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.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.8%
Patch available No
Active threat No
Deciding rule
Vendor states no customer action required
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Out-of-Cycle
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact
Very High
Technical Impact
Total

Priority Score

53
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +47
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: +5

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