PatchTheCVECVE-2026-71403: A flaw was found in Rancher Manager
CVE-2026-71403 is a medium-severity flaw (CVSS 6.1) affecting rancher. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- No elevated risk signals yet
A fixed release or distro patch exists.
Risk facts
| CVSS score | 6.1 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | High |
| User interaction | Required |
| EPSS exploit chance | 0.4% (top 70%) |
| CISA exploited list | No |
| Weakness | CWE-639 |
| Published | 2026-09-03 |
| Last modified | 2026-09-18 |
Last updated 2026-09-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-71403?
rancher: upgrade to 2.15.1. Exact commands for each OS are on this page.
Is CVE-2026-71403 being exploited?
CVE-2026-71403 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-71403 affect?
CVE-2026-71403 affects rancher. Severity is medium (CVSS 6.1). 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 i
How urgent is CVE-2026-71403?
Priority 29/100. No elevated risk signals yet.
Software pages
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