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CVE-2026-56817
critical
CVSS 9.8
XXE (XML External Entity) in io.netty:netty-codec-xml (CVE-2026-56817)
Summary
vulnerability in io.netty:netty-codec-xml (CVE-2026-56817). Successful exploitation can lead to full system takeover. Exploitable via ``XmlDecoder``. Mitigation: upgrade to `4.1.136.Final` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-56817** has been found in io.netty:netty-codec-xml.
Attackers can target a specific entry point like ``XmlDecoder`` over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: upgrade io.netty:netty-codec-xml to **4.1.136.Final** or later.
If unsure, ask your IT team or search "io.netty:netty-codec-xml CVE-2026-56817" on the vendor's site.
CVE-2026-56817 (io.netty:netty-codec-xml) — CWE-611 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: `XmlDecoder`
Patched: `4.1.136.Final` — 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-611) exists in io.netty:netty-codec-xml. Attackers reach the vulnerable code path via ``XmlDecoder`` without authentication.
📍 Affected scope
io.netty:netty-codec-xml — . Attack surface: `XmlDecoder`.
🔥 Severity
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover
🔧 How to fix
Update to **4.1.136.Final**.
🛡️ 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 'io.netty:netty-codec-xml' .` 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 'io.netty:netty-codec-xml' . | 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 `io.netty:netty-codec-xml` 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 io.netty:netty-codec-xml to 4.1.136.Finalステージング環境で 4.1.136.Final 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
maven
io.netty:netty-codec-xml
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.1.136.Final"}]}]