Rancher does not Properly Validate Account Bindings in SAML Authentication Enables User Impersonation on First Login

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.4 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L

EPSS

• CVE-2025-23389: 0.48% estimated exploitation activity in the next 30 days; percentile 41.21 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact A vulnerability in Rancher has been discovered, leading to a local user impersonation through SAML Authentication on first login. The issue occurs when a SAML authentication provider (AP) is configured (e.g. Keycloak). A newly created AP user can impersonate any user on Rancher by manipulating cookie values during their initial login to Rancher. This vulnerability could also be exploited if a Rancher user (present on the AP) is removed, either manually or automatically via the User Retention feature with delete-inactive-user-after. More precisely, Rancher validates only a subset of input from the SAML assertion request; however, it trusts and uses values that are not properly validated. An attacker could then configure the samlRancherUserID cookie and the samlRancherAction cookie so that the user principal from the AP will be added to the user specified by the attacker (from samlRancherUserID). Rancher can then be deceived by setting samlRancherUserID to the admin's user ID…

Published by the source

27 Feb 2025, 18:27 UTC

Last modified by the source

27 May 2025, 17:54 UTC

Source last checked

26 Oct 2026, 15:09 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-mq23-vvg7-xfm4

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# Patch Next advisory brief: CVE-2025-23389

Advisory: Rancher does not Properly Validate Account Bindings in SAML Authentication Enables User Impersonation on First Login
IDs: CVE-2025-23389, GHSA-mq23-vvg7-xfm4
Record: https://patchnext.com/advisories/cve-2025-23389 (revision 1, source checked 26 Oct 2026, 15:09 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/rancher/rancher 2.10.3, 2.9.7, 2.8.13. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/rancher/rancher: affected >= 2.8.0, < 2.8.13; >= 2.9.0, < 2.9.7; >= 2.10.0, < 2.10.3; fixed in 2.9.7, 2.8.13, 2.10.3

## Suggested inspection (read-only)
- Go github.com/rancher/rancher: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/rancher/rancher.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-mq23-vvg7-xfm4 (GitHub-reviewed advisory GHSA-mq23-vvg7-xfm4 lists affected ranges: Go github.com/rancher/rancher >=2.8.0 =2.9.0 =2.10.0 <2.10.3)

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