Arbitrary Command Injection Affecting k3s package, versions <1.35.2.1-r5


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.24% (47th percentile)

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  • Snyk IDSNYK-WOLFILATEST-K3S-15874102
  • published2 Apr 2026
  • disclosed27 Mar 2026

Introduced: 27 Mar 2026

CVE-2026-32241  (opens in a new tab)
CWE-77  (opens in a new tab)

How to fix?

Upgrade Wolfi k3s to version 1.35.2.1-r5 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream k3s package and not the k3s package as distributed by Wolfi. See How to fix? for Wolfi relevant fixed versions and status.

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 Base Scores

version 3.1