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CVE-2026-48491— Traefik: SNICheck ignores wildcard TLSOptions mappings, allowing domain-fronted mTLS bypass

Quick assessment

Affected
traefik traefik
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Traefik是Traefik公司开源的一款反向代理与负载均衡工具。 Traefik 3.7.0版本至3.7.3之前版本存在授权问题漏洞，该漏洞源于域前置保护（SNICheck）中存在仅使用精确映射查找解析HTTP Host标头的TLS选项且不应用通配符匹配，可能导致未经验证的客户端绕过通过通配符路由器TLSOptions强制实施的相互TLS。

CVSS 7.8 · High EPSS 0.36% · P27

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
traefik traefik >= 3.7.0, < 3.7.3 affected
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I. Basic Information for CVE-2026-48491

Vulnerability Information
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Vulnerability Title
Traefik: SNICheck ignores wildcard TLSOptions mappings, allowing domain-fronted mTLS bypass
Source: CVE Program / CVE List V5
Vulnerability Description
Traefik is an HTTP reverse proxy and load balancer. From 3.7.0 until 3.7.3, there is a high severity vulnerability in Traefik's domain-fronting protection (SNICheck) that allows an unauthenticated client to bypass mutual TLS enforced through wildcard router TLSOptions. When a router uses a wildcard host rule such as Host(*.example.com) with stricter TLS options (for example RequireAndVerifyClientCert), SNICheck resolves the TLS options for the HTTP Host header using exact map lookups only and never applies wildcard matching. If another permissive SNI is served on the same entrypoint, an attacker can complete the TLS handshake under the permissive options and then send an HTTP Host header targeting the wildcard-protected backend, reaching it without presenting a client certificate. This affects the regular HTTPS / HTTP-2 path and does not require HTTP/3. This vulnerability is fixed in 3.7.3.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用候选路径或通道进行的认证绕过
Source: CVE Program / CVE List V5
Vulnerability Title
Traefik 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Traefik是Traefik公司开源的一款反向代理与负载均衡工具。 Traefik 3.7.0版本至3.7.3之前版本存在授权问题漏洞，该漏洞源于域前置保护（SNICheck）中存在仅使用精确映射查找解析HTTP Host标头的TLS选项且不应用通配符匹配，可能导致未经验证的客户端绕过通过通配符路由器TLSOptions强制实施的相互TLS。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
traefik traefik >= 3.7.0, < 3.7.3 -

II. Public POCs for CVE-2026-48491

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III. Intelligence Information for CVE-2026-48491

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Vendor Advisories for CVE-2026-48491 (1)

Vendor Pages for CVE-2026-48491 (1)

Same Patch Batch · traefik · 2026-06-23 · 6 CVEs total

CVE-2026-53622 7.8 HIGH Traefik: HTTP/3 mTLS bypass via exact SNI TLSOptions lookup for wildcard and mixed-case ho
CVE-2026-48020 7.8 HIGH Traefik StripPrefix Route-Level Auth Bypass via Path Normalization
CVE-2023-54365 7.5 HIGH Traefik - Denial of Service via HTTP/2 Request Handling
CVE-2026-54762 Traefik Kubernetes Ingress NGINX provider fails open when auth-secret resolution fails
CVE-2026-54761 Traefik: Kubernetes Gateway crossProviderNamespaces bypass allows HTTPRoute outside the al

IV. Related Vulnerabilities

Same product: traefik
Same vendor: traefik
Same weakness: CWE-288

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