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CVE-2026-44938 high CVSS 8.8

Vulnerability in github.com/rancher/fleet (CVE-2026-44938)

Summary

Vulnerability in github.com/rancher/fleet (CVE-2026-44938). Successful exploitation can lead to full system takeover. Exploitable via namespaceLabels. Mitigation: upgrade to 0.12.15 or later.

Original description

The description as published by the source.

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:

  1. Review your system for potentially leaked credentials.
  2. 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 upg…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-44938 has been found in github.com/rancher/fleet.
Attackers can target a specific entry point like namespaceLabels over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: upgrade github.com/rancher/fleet to 0.12.15 or later.
If unsure, ask your IT team or search "github.com/rancher/fleet CVE-2026-44938" on the vendor's site.

CVE-2026-44938 (github.com/rancher/fleet) — CWE-522 / CVSS v3 8.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: namespaceLabels / fleet.yaml / BundleDeployment
Patched: 0.12.15 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-522) exists in github.com/rancher/fleet. Attackers reach the vulnerable code path via namespaceLabels.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/rancher/fleet. Attack surface: namespaceLabels / fleet.yaml / BundleDeployment.

🔥 Severity

Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 0.12.15.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/rancher/fleet' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'github.com/rancher/fleet' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で github.com/rancher/fleet を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade github.com/rancher/fleet to 0.12.15

    ステージング環境で 0.12.15 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

go github.com/rancher/fleet
[{"type":"SEMVER","events":[{"introduced":"0.12.0"},{"fixed":"0.12.15"}]}]

References

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