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CVE-2026-48491 critical CVSS 10.0

Vulnerability in Traefik (CVE-2026-48491)

Summary

Vulnerability in Traefik (CVE-2026-48491). Confidential information can be exposed externally. Mitigation: upgrade to 3.7.3 or later.

Original description

The description as published by the source.

The SNICheck middleware in Traefik ignores wildcard TLSOptions mappings, allowing an unauthenticated attacker to bypass mTLS requirements by using a domain-fronted request. This occurs because the middleware compares the TLS options name used during the handshake with a pre-computed value that may not account for wildcard matches correctly when certain configuration models are applied.

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-2026-48491 has been found in Traefik.
Confidential information can be exposed externally. CVSS score: 10.0/10.
What to do: upgrade Traefik to 3.7.3 or later.
If unsure, ask your IT team or search "Traefik CVE-2026-48491" on the vendor's site.

CVE-2026-48491 (Traefik) — CWE-288 / CVSS v3 10.0
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 3.7.3 — 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-288) exists in Traefik.

📍 Affected scope

Check the vendor advisory for the affected versions of Traefik.

🔥 Severity

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

🔧 How to fix

Update to 3.7.3.

🛡️ 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 'Traefik' . 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 'Traefik' . | 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 Traefik 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 Traefik to 3.7.3

    ステージング環境で 3.7.3 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 Traefik
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.7.3"}]}]
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"},{"fixed":"3.7.3"}]}]

References

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