Microsoft Azure Backup for AKS 2026-03-17 confused deputy ⚔ [Disputed]

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.7$0-$5k0.00

Summaryinfo

A vulnerability was found in Microsoft Azure Backup for AKS 2026-03-17. It has been rated as critical. Impacted is an unknown function of the component Backup Handler. Performing a manipulation results in confused deputy. The attack is possible to be carried out remotely. Moreover, an exploit is present. It is still unclear if this vulnerability genuinely exists. This product is a managed service, which means users themselves cannot handle vulnerability countermeasures. It is recommended to apply a patch to fix this issue. Microsoft, CERT/CC, and MITRE rejected a CVE assignment.

Detailsinfo

A vulnerability was found in Microsoft Azure Backup for AKS 2026-03-17. It has been classified as critical. This affects an unknown function of the component Backup Handler. The manipulation with an unknown input leads to a confused deputy vulnerability. CWE is classifying the issue as CWE-441. The product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere. This causes the product to appear to be the source of the request, leading it to act as a proxy or other intermediary between the upstream component and the external actor. This is going to have an impact on confidentiality, integrity, and availability.

It is possible to read the advisory at olearysec.com. The exploitability is told to be easy. It is possible to initiate the attack remotely. Additional levels of successful authentication are required for exploitation. Technical details are unknown but an exploit is available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/01/2026).

It is declared as proof-of-concept. The real existence of this vulnerability is still doubted at the moment. Microsoft, CERT/CC, and MITRE rejected a CVE assignment.

Applying a patch is able to eliminate this problem.

Further details are available at bleepingcomputer.com. Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Managed Service

  • yes

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.5
VulDB Meta Temp Score: 7.7

VulDB Base Score: 7.2
VulDB Temp Score: 6.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

Researcher Base Score: 9.9
Researcher Vector: 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Confused deputy
CWE: CWE-441
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Proof-of-Concept
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Status: 🔍

0-Day Time: 🔒

Timelineinfo

06/01/2026 Advisory disclosed
06/01/2026 +0 days VulDB entry created
06/01/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com

Advisory: VU#284781
Status: Confirmed
Disputed: 🔍

CVE: Not possible due to CNA Operational Rules
GCVE (VulDB): GCVE-100-367647
scip Labs: https://www.scip.ch/en/?labs.20161013
Misc.: 🔒

Entryinfo

Created: 06/01/2026 15:56
Updated: 06/01/2026 18:55
Changes: 06/01/2026 15:56 (59), 06/01/2026 18:52 (5), 06/01/2026 18:53 (6), 06/01/2026 18:55 (3)
Complete: 🔍
Submitter: olearysec
Committer: olearysec
Cache ID: 216::103

Submitinfo

Accepted

  • Submit #828539: Azure 2026-03-17 Incorrect Privilege Assignment (by olearysec)

Be aware that VulDB is the high quality source for vulnerability data.

Discussion

 olearysec (+1)
2 months ago
Behavioral evidence of remediation:

Prior to May 2026, Azure Backup for AKS allowed any principal with Backup Contributor role to configure Trusted Access bindings to arbitrary AKS clusters, bypassing RBAC authorization. Exploitation yielded cluster-admin.

Current behavior: Same operation now returns error code "UserErrorTrustedAccessGatewayReturnedForbidden" — an authorization check that did not exist previously.

This behavioral change confirms Microsoft addressed the vulnerability without acknowledgment.

Validation:
- CERT/CC VU#284781 — independently validated April 16, 2026

Coverage of silent patch:
- BleepingComputer, Zero Day (Kim Zetter), The Hacker News, SC Media

Technical disclosure: https://olearysec.com/research/azure-backup-aks-silent-patch/

The "disputed" status reflects Microsoft's initial triage response, not the current remediated state.
 olearysec (+0)
2 months ago
Technical clarification on privilege level:

Backup Contributor is a low-privilege Azure RBAC role. It grants zero Kubernetes permissions and is routinely delegated to backup operators. PR:L is the correct classification.

The attack also crosses trust boundaries (Azure RBAC → Kubernetes RBAC), which per CVSS 3.1 Section 2.2 constitutes Scope Changed (S:C).

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