CVE-2026-41050 — fleet
CRITICALCVE-2026-41050 is a critical-severity (CVSS 9.9) CWE-863 vulnerability in github.com/rancher/fleet. A fix is available for github.com/rancher/fleet — see the affected versions and patch details below.
Fleet: Helm impersonation bypass of `RESTClientGetter` retains `cluster-admin` during template rendering
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41050.
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.
How urgent is this, really
CVE-2026-41050 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/rancher/fleet🐹github.com/rancher/fleet🐹github.com/rancher/fleet🐹github.com/rancher/fleet🐹github.com/rancher/fleetReal-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
Fleet's Helm deployer did not fully apply ServiceAccount impersonation in two code paths, allowing a tenant with git push access to a Fleet-monitored repository to read secrets from any namespace on every downstream cluster targeted by their GitRepo.
Helm lookup bypass: The Helm template engine ran Kubernetes API queries with the fleet-agent's cluster-admin credentials instead of the impersonated ServiceAccount. A chart template could therefore access resources beyond the tenant's RBAC scope.
valuesFrom bypass: Secret and ConfigMap references in fleet.yaml helm.valuesFrom were read using the fleet-agent's cluster-admin client. A tenant could reference resources in namespaces the impersonated ServiceAccount has no access to.
Both issues break Fleet's multi-tenant impersonation boundary. The leaked credentials may belong to external services, making the full impact non-deterministic.
Single-tenant deployments where all users are trusted are not affected.
Important:
- For the exposure of additional credentials, the final impact severity for confidentiality, integrity and availability is dependent on the permissions the leaked credentials have on their services.
- It is recommended to review for potentially leaked credentials in this scenario and to change them if deemed necessary.
Please consult the associated MITRE ATT&CK - Technique - Account Access Removal for further information about this category of attack.
Patches
Both issues are fixed by ensuring the Helm action configuration consistently uses the impersonated ServiceAccount credentials throughout all Helm operations.
Patched versions of Rancher include releases v2.14.1, v2.13.5, v2.12.9, and v2.11.13. For Rancher v2.10.11, users must manually update their Fleet deployment to versionv0.11.13.
Workarounds
No workaround fully mitigates the issue for multi-tenant deployments. The patches should be applied as soon as they are available.
The following measures reduce the attack surface but do not close either vulnerability:
- Restrict git push access to Fleet-monitored repositories to trusted users only. In a multi-tenant setup this removes the precondition entirely, but is often not operationally viable.
- Use
GitRepoRestrictionresources to limit which ServiceAccounts each namespace is allowed to use, restricting the set of users who can configure impersonation at all. - Audit deployed chart templates for
lookupcalls andfleet.yamlfiles for cross-namespacevaluesFromreferences as a detective control.
Resources
If there are 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 using the support matrix and product support lifecycle.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/rancher/fleet | ≥ 0.15.0&&< 0.15.1 | 0.15.1go get github.com/rancher/fleet@v0.15.1 |
| 🐹Go | github.com/rancher/fleet | ≥ 0.14.0&&< 0.14.5 | 0.14.5go get github.com/rancher/fleet@v0.14.5 |
| 🐹Go | github.com/rancher/fleet | ≥ 0.13.0&&< 0.13.10 | 0.13.10go get github.com/rancher/fleet@v0.13.10 |
| 🐹Go | github.com/rancher/fleet | ≥ 0.12.0&&< 0.12.14 | 0.12.14go get github.com/rancher/fleet@v0.12.14 |
| 🐹Go | github.com/rancher/fleet | ≥ 0.11.0&&< 0.11.13 | 0.11.13go get github.com/rancher/fleet@v0.11.13 |
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/fleet, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/rancher/fleet to 0.15.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41050 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-41050 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-41050. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-41050 in your dependencies?
O3 Security finds CVE-2026-41050 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.