CVE-2026-44936: Rancher Fleet Information Disclosure Flaw

CVE-2026-44936 Overview

CVE-2026-44936 is a credential exposure vulnerability in SUSE Rancher Fleet's bundle reader. When the helmRepoURLRegex field is not set on a GitRepo resource, Fleet forwards Helm BasicAuth credentials to any URL specified in the helm.repo field of a fleet.yaml file. Attackers with push access to Fleet-monitored git repositories can redirect authentication credentials to attacker-controlled hosts. The flaw is categorized as a Server-Side Request Forgery weakness [CWE-918]. Affected releases include Fleet 0.15 before 0.15.2, 0.14 before 0.14.6, 0.13 before 0.13.11, and 0.12 before 0.12.15.

Critical Impact
Attackers with git push permissions can exfiltrate Helm repository credentials by pointing the helm.repo field at an attacker-controlled URL, enabling supply-chain compromise of downstream Helm charts.

Affected Products

SUSE Rancher Fleet 0.15 before 0.15.2
SUSE Rancher Fleet 0.14 before 0.14.6
SUSE Rancher Fleet 0.13 before 0.13.11 and 0.12 before 0.12.15

Discovery Timeline

2026-07-06 - CVE-2026-44936 published to NVD
2026-07-06 - Last updated in NVD database

Technical Details for CVE-2026-44936

Vulnerability Analysis

SUSE Rancher Fleet is a GitOps-at-scale controller that reconciles Kubernetes cluster state from git repositories. Fleet parses fleet.yaml files inside monitored repositories to locate Helm charts and their associated repositories. The bundle reader component reads the helm.repo URL and, when authentication is configured, attaches BasicAuth credentials to outbound HTTP requests.

The intended safeguard is the helmRepoURLRegex field on the GitRepo custom resource. This field restricts which URLs may receive credentials. When operators omit this field, Fleet applies no allowlist and forwards credentials to any URL the fleet.yaml specifies. This behavior matches the Server-Side Request Forgery pattern described in [CWE-918].

Root Cause

The bundle reader lacks a secure default. Missing configuration of helmRepoURLRegex results in unrestricted credential forwarding rather than a deny-by-default posture. Fleet trusts repository content that any authorized git contributor can modify.

Attack Vector

An attacker who can push commits to a Fleet-monitored git repository modifies a fleet.yaml file to set helm.repo to a URL under attacker control. When Fleet reconciles the repository, its bundle reader issues an authenticated HTTP request to the attacker's endpoint. The attacker captures the Authorization: Basic header and reuses the credentials against the legitimate Helm registry. The GitHub Security Advisory GHSA-hx4v-cxpf-vh8m documents the technical scope.

Detection Methods for CVE-2026-44936

Indicators of Compromise

Outbound HTTPS requests from Fleet controller pods to Helm repository hostnames that are not part of your approved chart infrastructure.
fleet.yaml commits that introduce or modify the helm.repo field without a corresponding helmRepoURLRegex allowlist on the GitRepo resource.
Authentication events on the legitimate Helm registry originating from unexpected source IPs shortly after Fleet reconciliation cycles.

Detection Strategies

Audit all GitRepo custom resources in the fleet-local and fleet-default namespaces and flag any without a helmRepoURLRegex field configured.
Correlate git commit history for monitored repositories with Fleet controller egress traffic to identify helm.repo URL changes that trigger requests to new destinations.
Review Fleet controller logs for bundle reconciliation events that reference external Helm URLs outside your organization's registry allowlist.

Monitoring Recommendations

Enable egress network policies on the cattle-fleet-system namespace and log denied connections.
Alert on modifications to fleet.yaml files within monitored repositories, particularly changes to helm.repo, helm.username, or helm.password fields.
Rotate and monitor usage of Helm repository credentials referenced by Fleet secrets.

How to Mitigate CVE-2026-44936

Immediate Actions Required

Upgrade Fleet to 0.15.2, 0.14.6, 0.13.11, or 0.12.15 depending on your minor release branch.
Set the helmRepoURLRegex field on every GitRepo resource to restrict credential forwarding to approved Helm registry hostnames.
Rotate any Helm BasicAuth credentials referenced by Fleet secrets, since prior exposure cannot be ruled out.

Patch Information

SUSE has published fixed versions in the 0.12.15, 0.13.11, 0.14.6, and 0.15.2 releases. Refer to the GitHub Security Advisory GHSA-hx4v-cxpf-vh8m for the full remediation notes and version matrix.

Workarounds

Configure helmRepoURLRegex on all GitRepo resources to match only your trusted Helm registry hostnames until patching is complete.
Restrict push access to Fleet-monitored git repositories to a minimal set of trusted maintainers and require signed commits.
Apply Kubernetes NetworkPolicy rules on the Fleet controller namespace to block egress to any host outside the approved Helm registry list.

bash

# Example: restrict credential forwarding to a trusted Helm registry
apiVersion: fleet.cattle.io/v1alpha1
kind: GitRepo
metadata:
  name: example-repo
  namespace: fleet-default
spec:
  repo: https://git.example.com/team/charts.git
  branch: main
  helmRepoURLRegex: '^https://charts\.example\.com/.*$'