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CVE-2026-48020 critical CVSS 10.0

Path Traversal in github.com/traefik/traefik/v2 (CVE-2026-48020)

Summary

Path traversal in github.com/traefik/traefik/v2 (CVE-2026-48020). Confidential information can be exposed externally. Exploitable via GET /admin. Mitigation: upgrade to 2.11.48 or later.

Original description

The description as published by the source.

Summary

There is a high severity vulnerability in Traefik's StripPrefix middleware that allows an unauthenticated attacker to bypass route-level authentication and authorization. When a public router matches on a PathPrefix rule and applies the StripPrefix middleware, a request path containing .. or its percent-encoded form %2e%2e can match the public route at routing time and then, after the prefix is stripped and the path is normalized, resolve to a path served by a separate, authenticated router. As a result, an attacker can reach protected backend paths — such as admin or internal configuration endpoints — without satisfying the authentication middleware attached to the protected router.

Patches

For more information

If there are any questions or comments about this advisory, please open an issue.

Original Description

Traefik StripPrefix Route-Level Auth Bypass via Path Normalization (/api../)

Summary

A route-level authentication/authorization bypas was found in Traefik when PathPrefix-based public routes are combined with StripPrefix.

A request using /api../ or /api%2e%2e/ can avoid protected router rules at the routing stage, but after StripPrefix, the path is normalized and forwarded to the backend as a protecte…

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-2026-48020 has been found in github.com/traefik/traefik/v2.
Attackers can target a specific entry point like GET /admin over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 10.0/10.
What to do: upgrade github.com/traefik/traefik/v2 to 2.11.48 or later.
If unsure, ask your IT team or search "github.com/traefik/traefik/v2 CVE-2026-48020" on the vendor's site.

CVE-2026-48020 (github.com/traefik/traefik/v2) — CWE-22 / CVSS v3 10.0
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: GET /admin / GET /internal/config / GET /api/admin / GET /api/internal/config
Patched: 2.11.48 — 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

Path traversal (CWE-22) exists in github.com/traefik/traefik/v2. Attackers reach the vulnerable code path via GET /admin without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/traefik/traefik/v2. Attack surface: GET /admin / GET /internal/config / GET /api/admin / GET /api/internal/config.

🔥 Severity

Severity: Critical (CVSS 10.0/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 2.11.48.

🛡️ 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 requests with malformed payloads or SQL meta-characters. Run grep -r 'github.com/traefik/traefik/v2' . 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/v2' . | 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/v2 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' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'

    アクセスログで GET /admin 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/v2 to 2.11.48

    ステージング環境で 2.11.48 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 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/v2
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.11.48"}]}]
go github.com/traefik/traefik/v3
[{"type":"SEMVER","events":[{"introduced":"3.7.0-ea.1"},{"fixed":"3.7.3"}]}]
Go github.com/traefik/traefik
[{"type":"SEMVER","events":[{"introduced":"0"}]}]

References

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