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CVE-2026-41181 medium CVSS 5.8

Vulnerability in github.com/traefik/traefik/v2 (CVE-2026-41181)

Summary

Vulnerability in github.com/traefik/traefik/v2 (CVE-2026-41181). Risk of unauthorized operations or information disclosure. Exploitable via errors. Mitigation: upgrade to 2.11.44 or later.

Original description

The description as published by the source.

Summary

There is a medium severity information disclosure vulnerability in Traefik's errors (custom error pages) middleware. When the backend returns a response matching the configured status range, the middleware forwards the original request's complete header set, including Authorization, Cookie, and other authentication material, to the separate error page service rather than only the minimal context needed to render the error page. This behavior is undocumented: the documentation states only that Host is forwarded by default, so operators are not warned that sensitive credentials are shared across service boundaries. Deployments using the errors middleware with a distinct error page service may inadvertently expose end-user credentials to infrastructure that was not intended to receive them.

Patches

For more information

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

Original Description

Description

Traefik v3.6.13's supported HTTP errors middleware discloses sensitive request headers to the configured error page service when the original backend response matches the configured status range and the middleware takes its default header-forwarding path. In the reproduced configuration, the b…

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-2026-41181 has been found in github.com/traefik/traefik/v2.
Attackers can target a specific entry point like errors over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.8/10.
What to do: upgrade github.com/traefik/traefik/v2 to 2.11.44 or later.
If unsure, ask your IT team or search "github.com/traefik/traefik/v2 CVE-2026-41181" on the vendor's site.

CVE-2026-41181 (github.com/traefik/traefik/v2) — CWE-201 / CVSS v3 5.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: errors / Authorization / Cookie / Host
Patched: 2.11.44 — 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-201) exists in github.com/traefik/traefik/v2. Attackers reach the vulnerable code path via errors without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/traefik/traefik/v2. Attack surface: errors / Authorization / Cookie / Host.

🔥 Severity

Severity: Medium (CVSS 5.8/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 2.11.44.

🛡️ 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 '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
    Apply patch patch 
    Upgrade github.com/traefik/traefik/v2 to 2.11.44

    ステージング環境で 2.11.44 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。

  3. 3
    Post-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。

Affected packages

go github.com/traefik/traefik/v2
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.11.44"}]}]
go github.com/traefik/traefik/v3
[{"type":"SEMVER","events":[{"introduced":"3.7.0-rc.0"},{"fixed":"3.7.0-rc.3"}]}]
Go github.com/traefik/traefik
[{"type":"SEMVER","events":[{"introduced":"0"}]}]

References

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