Rancher: Identity-field mutation in /v3/users allows account hijack via principal rebind

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-71403
StatePUBLISHED
Assignersuse
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-03 15:17:32 UTC
Updated2026-09-08 19:12:59 UTC
DescriptionA 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.

Risk And Classification

Primary CVSS: v3.1 6.1 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N

EPSS: 0.001970000 probability, percentile 0.094500000 (date 2026-09-08)

Problem Types: CWE-639 | CWE-639 CWE-639 Authorization bypass through User-Controlled key

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.1MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N
3.1CNACVSS6.1MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA SUSE Rancher affected 2.15.1 semver Not specified

References

ReferenceSourceLinkTags
github.com/rancher/rancher/pull/56616 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Andrej Tomči (en)

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