Auth bypass in SUSE Rancher

CVE-2026-71403

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.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.004 (29.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 29th percentile — 29.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-71403: held from 0.002 to 0.004.

EPSS over last 30 days · oldest: 0.002 · newest: 0.004 · change: +0.002

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-71403?
CVE-2026-71403 is a medium-severity vulnerability in SUSE Rancher, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.1/10. Published 2026-09-03.
How severe is CVE-2026-71403?
Medium severity. CVSS v3 base score is 6.1 out of 10.