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CVE-2021-25748
Vulnerability in k8s.io/ingress-nginx (CVE-2021-25748)
Summary
vulnerability in k8s.io/ingress-nginx (CVE-2021-25748). Confidential information can be exposed externally. Exploitable via ``networking.k8s.io``. Mitigation: upgrade to `1.2.1` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2021-25748** has been found in k8s.io/ingress-nginx.
Attackers can target a specific entry point like ``networking.k8s.io`` over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: ?/10.
What to do: upgrade k8s.io/ingress-nginx to **1.2.1** or later.
If unsure, ask your IT team or search "k8s.io/ingress-nginx CVE-2021-25748" on the vendor's site.
CVE-2021-25748 (k8s.io/ingress-nginx) — CWE-20 /
Attack vector: remote (network-reachable) / no user interaction
Attack surface: `networking.k8s.io` / `extensions`
Patched: `1.2.1` — 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-20) exists in k8s.io/ingress-nginx. Attackers reach the vulnerable code path via ``networking.k8s.io`` without authentication.
📍 Affected scope
k8s.io/ingress-nginx — . Attack surface: `networking.k8s.io` / `extensions`.
🔥 Severity
Severity: ?. Confidential information can be exposed externally
🔧 How to fix
Update to **1.2.1**.
🛡️ 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 'k8s.io/ingress-nginx' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'k8s.io/ingress-nginx' . | 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 `k8s.io/ingress-nginx` を grep し、稼働しているサービス・バージョンを把握する。
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6Apply patch patch
Upgrade k8s.io/ingress-nginx to 1.2.1ステージング環境で 1.2.1 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
Go
k8s.io/ingress-nginx
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.2.1"}]}]
References
- advisory https://nvd.nist.gov/vuln/detail/CVE-2021-25748
- package https://github.com/kubernetes/ingress-nginx
- web https://groups.google.com/g/kubernetes-security-announce/c/avaRYa9c7I8
- web https://github.com/kubernetes/ingress-nginx/issues/8686
- web https://github.com/kubernetes/ingress-nginx/pull/8623
- web https://github.com/kubernetes/ingress-nginx/releases/tag/controller-v1.2.1