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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-88008
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-10 15:17:56 UTC
Updated2026-09-10 17:17:07 UTC
DescriptionTraefik 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.

Risk And Classification

Primary CVSS: v4.0 7 HIGH from [email protected]

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-444 | CWE-863 | CWE-444 CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') | CWE-863 CWE-863: Incorrect Authorization

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary7HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/C...
4.0CNADECLARED7HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
None
Availability
None
Sub Conf.
High
Sub Integrity
High
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Traefik Traefik affected >= 2.11.26, < 2.11.57 Not specified
CNA Traefik Traefik affected >= 3.4.2, < 3.7.13 Not specified

References

ReferenceSourceLinkTags
github.com/traefik/traefik/releases/tag/v3.7.13 [email protected] github.com
github.com/traefik/traefik/pull/13797 [email protected] github.com
github.com/traefik/traefik/releases/tag/v2.11.57 [email protected] github.com
github.com/traefik/traefik/security/advisories/GHSA-w4v4-9rw7-5326 [email protected] github.com
github.com/traefik/traefik/commit/a277e94664ffc1ce9543df552d3bbf48d4d3b8b3 [email protected] github.com
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