Vulnerability Description
Flannel is a network fabric for containers, designed for Kubernetes. The Flannel project includes an experimental Extension backend that allows users to easily prototype new backend types. In versions of Flannel prior to 0.28.2, this Extension backend is vulnerable to a command injection that allows an attacker who can set Kubernetes Node annotations to achieve root-level arbitrary command execution on every flannel node in the cluster. The Extension backend's SubnetAddCommand and SubnetRemoveCommand receive attacker-controlled data via stdin (from the `flannel.alpha.coreos.com/backend-data` Node annotation). The content of this annotation is unmarshalled and piped directly to a shell command without checks. Kubernetes clusters using Flannel with the Extension backend are affected by this vulnerability. Other backends such as vxlan and wireguard are unaffected. The vulnerability is fixed in version v0.28.2. As a workaround, use Flannel with another backend such as vxlan or wireguard.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Flannel-Io | Flannel | < 0.28.2 |
Related Weaknesses (CWE)
References
- https://github.com/flannel-io/flannel/releases/tag/v0.28.2ProductRelease Notes
- https://github.com/flannel-io/flannel/security/advisories/GHSA-vchx-5pr6-ffx2MitigationVendor Advisory
FAQ
What is CVE-2026-32241?
CVE-2026-32241 is a vulnerability with a CVSS score of 7.5 (HIGH). Flannel is a network fabric for containers, designed for Kubernetes. The Flannel project includes an experimental Extension backend that allows users to easily prototype new backend types. In versions...
How severe is CVE-2026-32241?
CVE-2026-32241 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-32241?
Check the references section above for vendor advisories and patch information. Affected products include: Flannel-Io Flannel.