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CVE-2026-88009 high CVSS 8.2

Vulnerability in github.com/traefik/traefik/v3 (CVE-2026-88009)

Summary

Vulnerability in github.com/traefik/traefik/v3 (CVE-2026-88009). Confidential information can be exposed externally. Exploitable via GET /admin/secret. Mitigation: upgrade to 3.7.13 or later.

Original description

The description as published by the source.

Summary

Traefik accepts an HTTP/1.x request whose request-target is in rootless / opaque form (for example GET http:http://internal-vhost/admin HTTP/1.1). Go parses this into URL.Opaque with an empty URL.Path, so Traefik evaluates all routing, path-sanitization, middleware and access-log decisions against a path that normalizes to /, while the proxy forwards the attacker's original target byte-for-byte to the backend. Router path/prefix guards, forwardAuth path-scoped policies and the encodedCharacters hardening never see the real target, and the access log records every such request as GET / HTTP/1.1. Against a backend that resolves a rootless target as a path, this yields cross-vhost routing bypass, path-scoped authorization bypass and access-log evasion — unauthenticated, with stock entrypoint defaults.

Traefik v3.0 through v3.6 are end-of-life and are also affected; they will not receive a fix on their own line. Users on those versions must upgrade to v3.7.13.

Patches

For more information

If you have any questions or comments about this advisory, please open an issue.

Original Description

Summary

The scanner claims rewriteRequestBuilder (pkg/proxy/httputil/proxy.go:97) rebuilds the outbound target from URL.Path / RawPath / RawQuery but never clears URL.Opaque, so a c…

Source: NIST National Vulnerability Database 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-2026-88009 has been found in github.com/traefik/traefik/v3.
Attackers can target a specific entry point like GET /admin/secret over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.2/10.
What to do: upgrade github.com/traefik/traefik/v3 to 3.7.13 or later.
If unsure, ask your IT team or search "github.com/traefik/traefik/v3 CVE-2026-88009" on the vendor's site.

CVE-2026-88009 (github.com/traefik/traefik/v3) — CWE-444 / CVSS v3 8.2
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: GET /admin/secret / URL.Opaque / URL.Path / forwardAuth
Patched: 3.7.13 — 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-444) exists in github.com/traefik/traefik/v3. Attackers reach the vulnerable code path via GET /admin/secret without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/traefik/traefik/v3. Attack surface: GET /admin/secret / URL.Opaque / URL.Path / forwardAuth.

🔥 Severity

Severity: High (CVSS 8.2/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 3.7.13.

🛡️ 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 GET /admin/secret requests with malformed payloads or SQL meta-characters. Run grep -r 'github.com/traefik/traefik/v3' . 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/traefik/traefik/v3' . | 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/traefik/traefik/v3 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
    Hunt for indicators of compromise detect 
    grep 'GET /admin/secret' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで GET /admin/secret への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。

  3. 3
    Apply patch patch 
    Upgrade github.com/traefik/traefik/v3 to 3.7.13

    ステージング環境で 3.7.13 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 2 で見つけた異常検知の続報チェックを含めること。

  4. 4
    Post-deployment verification verify 
    Replay attack against GET /admin/secret on staging to confirm patch closes the vector

    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 2 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 github.com/traefik/traefik/v3
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.7.13"}]}]
go github.com/traefik/traefik/v2
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.11.57"}]}]

References

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