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CVE-2026-88008— Traefik: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization

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公司开源的一款负载均衡器。 Traefik 2.11.26版本至2.11.57之前版本和3.4.2版本至3.7.13之前版本存在安全漏洞，该漏洞源于Traefik将客户端提供的请求Upgrade的Connection标头、Upgrade: h2c令牌和HTTP2-Settings转发到共享后端，当后端接受h2c并返回101 Switching Protocols时进入原始隧道，不再对后续HTTP/2请求应用路由器、BasicAuth、ForwardAuth、IPAllowLi

CVSS 7.0 · High EPSS 0.49% · P42 Updated Sep 11, 2026

Possible ATT&CK Techniques 1 AI

T1557.001 · Name Resolution Poisoning and SMB Relay

Affected Version Matrix 2

Vendor	Product	Version Range	Status
traefik	traefik	`>= 2.11.26, < 2.11.57`	affected
		`>= 3.4.2, < 3.7.13`	affected

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I. Basic Information for CVE-2026-88008

Vulnerability Information

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Vulnerability Title

Traefik: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization

Source: CVE Program / CVE List V5

Vulnerability Description

Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.26 until 2.11.57 and 3.7.13, Traefik forwards a client-supplied Connection header requesting Upgrade, the Upgrade: h2c token, and HTTP2-Settings to a shared backend. If the backend accepts h2c and returns 101 Switching Protocols, Traefik enters a raw tunnel and no longer applies routers, BasicAuth, ForwardAuth, IPAllowList, RateLimit, access logging, metrics, or tracing to later HTTP/2 requests, allowing an unauthenticated request through an unprotected route to reach protected paths on the same backend. This issue is fixed in 2.11.57 and 3.7.13.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Source: CVE Program / CVE List V5

Vulnerability Type

HTTP请求的解释不一致性(HTTP请求私运)

Source: CVE Program / CVE List V5

Vulnerability Title

Traefik 输入验证错误漏洞

Source: CNNVD (China National Vulnerability Database)

Vulnerability Description

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	>= 2.11.26, < 2.11.57	-

II. Public POCs for CVE-2026-88008

#	POC Description	Source Link	Shenlong Link

AI-Generated POC Premium

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III. Intelligence Information for CVE-2026-88008

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Patches & Fixes for CVE-2026-88008 (2)

Vendor Advisories for CVE-2026-88008 (1)

🔗 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization in github.com/traefik/traefik/v3 · Advisory · traefik/traefik · GitHub Read full article x_refsource_CONFIRM

Vendor Pages for CVE-2026-88008 (2)

🔗 Release v3.7.13 · traefik/traefik · GitHub Read full article x_refsource_MISC
🔗 Release v2.11.57 · traefik/traefik · GitHub x_refsource_MISC

https://www.cve.org/CVERecord?id=CVE-2026-88008

Same Patch Batch · traefik · 2026-09-10 · 9 CVEs total

CVE-2026-88877	9.8 CRITICAL	Traefik v3.7.0 Authentication Bypass via from-to-www-redirect
CVE-2026-88007	9.1 CRITICAL	Traefik HTTP/3 Backend NTLM Connection Reuse
CVE-2026-88009	8.8 HIGH	Traefik: Rootless HTTP/1 request-target routes as "/" but is forwarded verbatim, bypassing
CVE-2026-88004	7.0 HIGH	Traefik entrypoint header-name sanitization bypassed via request trailers
CVE-2026-88879	5.3 MEDIUM	Traefik before v2.11.56 Identity Spoofing via Header Alias
CVE-2026-88878	5.3 MEDIUM	Traefik v2.8.2 through v3.6 HTTP/3 Timeout Bypass
CVE-2026-88011	5.3 MEDIUM	Traefik: ForwardAuth identity spoofing via dot-form header alias
CVE-2026-88012	5.3 MEDIUM	Traefik: respondingTimeouts.readTimeout is not applied to HTTP/3, leaving slow-body upload

IV. Related Vulnerabilities

Same product: traefik

Same vendor: traefik

Same weakness: CWE-444