CVE-2026-44935 — fleet
CRITICALCVE-2026-44935 is a critical-severity (CVSS 9.9) CWE-1287 vulnerability in github.com/rancher/fleet. A fix is available for github.com/rancher/fleet — see the affected versions and patch details below.
Rancher Fleet vulnerable to cross namespace secret disclosure via unvalidated `valuesFrom` references in Helm Deployer
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-2026-44935.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-44935 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 381,682 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
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
A vulnerability in Fleet for Rancher Manager affects multi-tenancy environments where different tenants share the same downstream clusters (e.g., different privileged or untrusted teams inside the same organization).
On unpatched versions, tenants could bypass restrictions to access any config map or secret across all namespaces on the downstream cluster. They can create cluster-wide resources using HelmOp or Bundle without authorization.
Specifically, an attacker can exploit this vulnerability in the following ways:
- Use
valuesFrominfleet.yaml(through aGitReporesource) or a `HelmOp resource to read the contents of any secret an on the downstream cluster, provided they know or can guess the name, namespace, and key. - Deploy
HelmOpandBundleresources without being restricted to a specific service account for the Fleet agent.
If you use Fleet in a multi-tenant environment, it's recommended that you:
- Review your cluster and Fleet deployments logs for indicators of unauthorized access across tenant namespaces.
- Rotate any service accounts and credentials that might have been exposed.
Please consult the associated MITRE ATT&CK - Technique - Unsecured Credentials for further information about this category of attack.
Patches
To resolve this vulnerability, upgrade to a patched version of Fleet. The new Policy resource allows you to:
- Configure
GitRepos,HelmOps, andBundlesto require a specific service account for the Fleet agent on downstream clusters used for deployment. The agent uses these designated service accounts for operations, blocking access to unauthorized resources. - Restrict
HelmOprepository and chart URLs by using a regular expression. The regular expression is automatically anchored with^and$, meaning it must match the entire URL string.
Like GitRepoRestriction, a Policy resource must be created in the specific namespace you want to restrict, and it only applies to that namespace.
Note: Before applying a policy, ensure that the required service account is available on the downstream clusters and is configured with least-privilege permissions.
Patched versions of Fleet include releases v0.15.2, v0.14.6, 0.13.11, and v0.12.15.
Workarounds
If you can't upgrade to a fixed version, please make sure that tenants do not have shared access to the same downstream clusters.
Credits
This security issue was reported by the following collaborators according to our responsible disclosure policy:
- Radisauskas Arnoldas from NATO and the NATO Cyber Security Centre (NCSC).
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/fleet | ≥ 0.15.0&&< 0.15.2 | 0.15.2go get github.com/rancher/fleet@v0.15.2 |
| 🐹Go | github.com/rancher/fleet | ≥ 0.14.0&&< 0.14.6 | 0.14.6go get github.com/rancher/fleet@v0.14.6 |
| 🐹Go | github.com/rancher/fleet | ≥ 0.13.0&&< 0.13.11 | 0.13.11go get github.com/rancher/fleet@v0.13.11 |
| 🐹Go | github.com/rancher/fleet | ≥ 0.12.0&&< 0.12.15 | 0.12.15go get github.com/rancher/fleet@v0.12.15 |
Affected Products
rancher fleetsuseDetection & 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 0.15.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44935 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.
Frequently Asked Questions
Is CVE-2026-44935 in your dependencies?
Find it across Go, including transitive dependencies.