GHSA-mq23-vvg7-xfm4
HIGHRancher does not Properly Validate Account Bindings in SAML Authentication Enables User Impersonation on First Login
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
github.com/rancher/rancher🐹github.com/rancher/rancher🐹github.com/rancher/rancherReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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 saml_Rancher_UserID cookie and the saml_Rancher_Action cookie so that the user principal from the AP will be added to the user specified by the attacker (from saml_Rancher_UserID). Rancher can then be deceived by setting saml_Rancher_UserID to the admin's user ID and saml_Rancher_Action to testAndEnable, thereby executing the vulnerable code path and leading to privilege escalation.
Note that the vulnerability impacts all SAML APs available in Rancher. However the following Rancher deployments are not affected:
- Rancher deployments not using SAML-based AP.
- Rancher deployments using SAML-based AP, where all SAML users are already signed in and linked to a Rancher account.
Please consult the associated MITRE ATT&CK - Technique - Access Token Manipulation: Token Impersonation/Theft for further information about this category of attack.
Patches
This vulnerability is addressed by adding the UserID claim to a JWT signed token, which is protected against tampering.
Patched versions include releases v2.8.13, v2.9.7 and v2.10.3.
Workarounds
Rancher deployments that can't upgrade, could temporarily disable the SAML-based AP as a temporary workaround. However, upgrading is recommended.
References
If you have any questions or comments about this advisory:
- Reach out to the SUSE Rancher Security team for security related inquiries.
- Open an issue in the Rancher repository.
- Verify with our support matrix and product support lifecycle.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/rancher/rancher | ≥ 2.8.0&&< 2.8.13 | 2.8.13 |
| 🐹Go | github.com/rancher/rancher | ≥ 2.9.0&&< 2.9.7 | 2.9.7 |
| 🐹Go | github.com/rancher/rancher | ≥ 2.10.0&&< 2.10.3 | 2.10.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/rancher/rancher. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/rancher/rancher to 2.8.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mq23-vvg7-xfm4 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-mq23-vvg7-xfm4 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-mq23-vvg7-xfm4. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-mq23-vvg7-xfm4 in your dependencies?
O3 detects GHSA-mq23-vvg7-xfm4 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.