CVE-2026-71403
Received Received - Intake

Immutable Field Bypass in Rancher Manager

Publication date: 2026-09-03

Last updated on: 2026-09-03

Assigner: SUSE

Description
A flaw was found in Rancher Manager. The /v3/users update path did not enforce immutability of a User resource's `username` and `principalIds` fields. A user holding the `update` verb on `users.management.cattle.io` could inject a foreign identity provider principal into any account, so that the next login by the owner of that principal was bound to the victim's account and inherited its role bindings. This issue affects Rancher: before 2.15.1.

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Meta Information

Published
2026-09-03
Last Modified
2026-09-03
Generated
2026-09-03
AI Q&A
2026-09-03
EPSS Evaluated
N/A
NVD
CVE-2026-71403
EUVD
EUVD-2026-70501

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
rancher rancher to 2.15.1 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-639 The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

Attack-Flow Graph

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Executive Summary

This vulnerability in Rancher Manager allows a user with update permissions to inject a foreign identity provider principal into any account. This means when the legitimate account owner logs in next, their session is bound to the victim's account and inherits its permissions. The flaw exists because the /v3/users update path does not enforce immutability of the username and principalIds fields.

Impact Analysis

An attacker could gain unauthorized access to sensitive resources by hijacking another user's session. They could perform actions on behalf of the victim, such as modifying configurations, accessing confidential data, or escalating privileges. This is particularly dangerous for users with administrative roles.

Compliance Impact

This vulnerability could lead to unauthorized access to personal or sensitive data, violating GDPR's data protection principles and HIPAA's security requirements. Organizations using affected Rancher versions may face compliance violations, legal penalties, and reputational damage due to potential data breaches.

Mitigation Strategies

Upgrade Rancher Manager to version 2.15.1 or later to address the flaw in the /v3/users update path that allows unauthorized principal injection.

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