CVE-2026-44938
HIGHCVE-2026-44938 is a high-severity (CVSS 8.8) CWE-522 vulnerability in github.com/rancher/fleet. O3 Security confirms whether CVE-2026-44938 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Fleet has PSS Bypass through addLabelsFromOptions in Fleet Agent
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-2026-44938.
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-2026-44938 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 363,588 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/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 has been identified in Fleet's agent-side deployer, which did not filter security-sensitive keys from namespaceLabels in fleet.yaml (or BundleDeployment.spec.options.namespaceLabels) when applying them to the target namespace.
An attacker with git push access to a Fleet-monitored repository could overwrite Pod Security Standards (PSS) enforcement labels on a target namespace. This allows the attacker to weaken admission controls and deploy workloads that PSS policies would otherwise block.
Important: The final impact on confidentiality, integrity, and availability depends on the specific permissions of the leaked credentials.
Fleet team recommends you:
- Review your system for potentially leaked credentials.
- Replace any credentials that may be compromised.
Please consult the associated MITRE ATT&CK - Technique - Disable or Modify Tools for further information about this category of attack.
Patches
To fix this issue, upgrade to a patched version. The updated Fleet deployer filters out labels with the pod-security.kubernetes.io/ prefix when applying namespaceLabels to a namespace. This change preserves the PSS labels set by cluster administrators and prevents them from being overwritten through fleet.yaml or BundleDeployment options.
Patched versions of Fleet include releases v0.15.2, v0.14.6, v0.13.11, and v0.12.15.
Workarounds
If you can’t immediately upgrade to a patched version, use one of the following workarounds:
1 - Deploy NeuVector(primary workaround)
Deploy NeuVector (SUSE Security) and configure an admission control Deny rule for "Run as privileged" in Protect mode.
- NeuVector evaluates pod specs independently of Kubernetes PSS namespace labels. It blocks privileged containers even if the labels are downgraded.
- Although the namespace labels are still overwritten, the attack cannot exploit confidentiality, integrity, or availability without a privileged pod.
2 - Restrict repository access (secondary workaround)
Note: The following measure reduces the attack surface but does not close the vulnerability:
- In a multi-tenant setup, this restriction removes the primary attack vector. However, this measure only reduces the attack surface and doesn't completely close the vulnerability. It may also not be operationally viable for all organizations. ´
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
- 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 | 0.15.2 |
| 🐹Go | github.com/rancher/fleet | ≥ 0.14.0&&< 0.14.6 | 0.14.6 |
| 🐹Go | github.com/rancher/fleet | ≥ 0.13.0&&< 0.13.11 | 0.13.11 |
| 🐹Go | github.com/rancher/fleet | ≥ 0.12.0&&< 0.12.15 | 0.12.15 |
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. 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/fleet to 0.15.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44938 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 CVE-2026-44938 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 CVE-2026-44938. 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-2026-44938 in your dependencies?
O3 detects CVE-2026-44938 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.