What is CVE-2026-71403?

CVE-2026-71403 is a medium-severity vulnerability, 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.

CVE-2026-71403

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)

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.

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

meissner@suse.de

Frequently asked questions

What is CVE-2026-71403?: CVE-2026-71403 is a medium-severity vulnerability, 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.