---
id: CVE-2026-71403
title: A flaw was found in Rancher Manager
summary: >-
  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
  foreig…
severity: medium
cvss: 6.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N'
cwe:
  - CWE-639
vendor: suse
product: rancher
affected:
  - rancher < 2.15.1
patched:
  - rancher 2.15.1
published: '2026-09-03'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T15:03:02.433'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-71403'
references:
  - url: 'https://github.com/rancher/rancher/pull/56616'
    label: meissner@suse.de
tags:
  - nvd
epss: 0.00369
epssPercentile: 0.2796
ingestedAt: '2026-09-08T20:10:03.160Z'
---

## Overview

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.

## Affected

- `rancher < 2.15.1`

## Remediation

Upgrade past the affected range:

- `rancher 2.15.1`