Vulnerability in Envoy (CVE-2026-47220)
Summary
Vulnerability in Envoy (CVE-2026-47220). Risk of unauthorized operations or information disclosure. Exploitable via Host header. Mitigation: upgrade to 1.37.5 or later.
Original description
The description as published by the source.
Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.37.0 until 1.37.5 and 1.38.3, when the %REQUESTED_SERVER_NAME(X:Y)% is used in log format and host related options is specified, like HOST_FIRST, SNI_FIRST, it's possible to crash Envoy when the specified host header is missing in the request headers. This vulnerability is fixed in 1.37.5 and 1.38.3.
Source: NIST National Vulnerability Database NVD
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-2026-47220 has been found in Envoy.
Attackers can target a specific entry point like Host header over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade Envoy to 1.37.5 or later.
If unsure, ask your IT team or search "Envoy CVE-2026-47220" on the vendor's site.
CVE-2026-47220 (Envoy) — CWE-476 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Host header
Patched: 1.37.5 — 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.
A vulnerability (CWE-476) exists in Envoy. Attackers reach the vulnerable code path via Host header without authentication.
Check the vendor advisory for the affected versions of Envoy. Attack surface: Host header.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 1.37.5.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Envoy' . 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
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1Identify exposure identify
grep -r 'Envoy' . | 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
Envoyを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Envoy to 1.37.5ステージング環境で 1.37.5 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。
-
3Post-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。
References
- exploit github.com
- web access.redhat.com
- web bugzilla.redhat.com
- web security.access.redhat.com