Authorization Flaw in github.com/rancher/fleet (CVE-2026-44935)
Summary
Vulnerability in github.com/rancher/fleet (CVE-2026-44935). Successful exploitation can lead to full system takeover. Exploitable via HelmOp. Mitigation: upgrade to 0.12.15 or later.
Original description
The description as published by the source.
Missing validation of "valuesFrom" references in Helm Deployer of SUSE Rancher 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 could be used by owners of one tenant to access fleet credentials of other tenants.
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-2026-44935 has been found in github.com/rancher/fleet.
Attackers can target a specific entry point like HelmOp over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.9/10.
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-2026-44935" on the vendor's site.
CVE-2026-44935 (github.com/rancher/fleet) — CWE-863 / CVSS v3 9.9
Attack vector: remote (network-reachable) / no user interaction
Attack surface: HelmOp / Bundle / valuesFrom / fleet.yaml
Patched: 0.12.15 — apply immediately
Workaround: If you can't upgrade to a fixed version, please make sure that tenants do not have shared access to the same downstream clusters.
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.
Incorrect authorization (CWE-863) exists in github.com/rancher/fleet. Attackers reach the vulnerable code path via HelmOp.
Check the vendor advisory for the affected versions of github.com/rancher/fleet. Attack surface: HelmOp / Bundle / valuesFrom / fleet.yaml.
Severity: Critical (CVSS 9.9/10). Successful exploitation can lead to full system takeover.
Update to 0.12.15.
Workaround: If you can't upgrade to a fixed version, please make sure that tenants do not have shared access to the same downstream clusters.
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
-
1Identify 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。 -
2Apply temporary workaround mitigate
If you can't upgrade to a fixed version, please make sure that tenants do not have shared access to the same downstream clusters.パッチが適用されるまでの応急処置として、If you can't upgrade to a fixed version, please make sure that tenants do not have shared access to the same downstream clusters. を実施。回避策の副作用 (機能低下) を確認した上で。
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3Apply 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。
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4Post-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
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com