{"cve":"CVE-2026-32241","nvd":{"published":"2026-03-27T20:16:30.570","modified":"2026-06-17T10:35:24.630","status":"Analyzed","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":8.8},"cwes":["CWE-77"],"references":["https://github.com/flannel-io/flannel/releases/tag/v0.28.2","https://github.com/flannel-io/flannel/security/advisories/GHSA-vchx-5pr6-ffx2"],"products":["flannel-io:flannel"],"source":"nvd","synced_at":"2026-10-19T22:28:18.033120106+00:00"},"epss":{"cve":"CVE-2026-32241","score":0.02757,"percentile":0.8625,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-vchx-5pr6-ffx2","url":"https://osv.dev/vulnerability/GHSA-vchx-5pr6-ffx2","summary":"Flannel has cross-node remote code execution via extension backend BackendData injection","modified":"2026-09-10T03:50:41.275757864Z","packages":[{"ecosystem":"Go","name":"github.com/flannel-io/flannel","purl":"pkg:golang/github.com/flannel-io/flannel","ranges":["<0.28.2"],"fixed":["0.28.2"]}]},{"id":"GO-2026-4894","url":"https://osv.dev/vulnerability/GO-2026-4894","summary":"Flannel has cross-node remote code execution via extension backend BackendData injection in github.com/flannel-io/flannel","modified":"2026-05-06T20:44:10.025800769Z","packages":[{"ecosystem":"Go","name":"github.com/flannel-io/flannel","purl":"pkg:golang/github.com/flannel-io/flannel","ranges":["<0.28.2"],"fixed":["0.28.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}