CVE-2026-39858

Published: Apr 30, 2026 Last Modified: Mag 01, 2026
ExploitDB:
Other exploit source:
Google Dorks:
HIGH 7,8
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: none
User Interaction: none
Confidentiality: N/A
Integrity: N/A
Availability: N/A
CRITICAL 10,0
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: none
User Interaction: none
Scope: changed
Confidentiality: high
Integrity: high
Availability: none

Description

AI Translation Available

Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a high severity authentication bypass vulnerability in Traefik's ForwardAuth and snippet-based authentication middleware. Traefik's forwarded-header sanitization logic targets only canonical header names (e.g., X-Forwarded-Proto) and does not strip or normalize alias variants that use underscores instead of dashes (e.g., X_Forwarded_Proto). These unsanitized alias headers are forwarded intact to the authentication backend. When the backend normalizes underscore and dash header forms equivalently, an attacker can inject spoofed trust context — such as a trusted scheme or host — through the alias headers and bypass authentication on protected routes without valid credentials. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.

EPSS (Exploit Prediction Scoring System)

Trend Analysis

EPSS (Exploit Prediction Scoring System)

Prevede la probabilità di sfruttamento basata su intelligence sulle minacce e sulle caratteristiche della vulnerabilità.

EPSS Score
0,0005
Percentile
0,2th
Updated

Single Data Point

Only one EPSS measurement is available for this CVE. Trend analysis requires multiple data points over time.

290

Authentication Bypass by Spoofing

Incomplete
Abstraction: Base Structure: Simple
Common Consequences
Security Scopes Affected:
Access Control
Potential Impacts:
Bypass Protection Mechanism Gain Privileges Or Assume Identity
Applicable Platforms
All platforms may be affected
View CWE Details
306

Missing Authentication for Critical Function

Draft
Abstraction: Base Structure: Simple
Common Consequences
Security Scopes Affected:
Access Control Other
Potential Impacts:
Gain Privileges Or Assume Identity Varies By Context
Applicable Platforms
Technologies: Cloud Computing, ICS/OT
Likelihood of Exploit: High
View CWE Details
Application

Traefik by Traefik

Product Information
Vendor Traefik
Product Traefik
Version Range Affected
To 2.11.43 (exclusive)
cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
Application

Traefik by Traefik

Product Information
Vendor Traefik
Product Traefik
Version 3.7.0
cpe:2.3:a:traefik:traefik:3.7.0:ea1:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
Application

Traefik by Traefik

Product Information
Vendor Traefik
Product Traefik
Version 3.7.0
cpe:2.3:a:traefik:traefik:3.7.0:rc1:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
Application

Traefik by Traefik

Product Information
Vendor Traefik
Product Traefik
Version Range Affected
From 3.0.0 (inclusive)
To 3.6.14 (exclusive)
cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
Application

Traefik by Traefik

Product Information
Vendor Traefik
Product Traefik
Version 3.7.0
cpe:2.3:a:traefik:traefik:3.7.0:ea2:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
Application

Traefik by Traefik

Product Information
Vendor Traefik
Product Traefik
Version 3.7.0
cpe:2.3:a:traefik:traefik:3.7.0:ea3:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
https://github.com/traefik/traefik/releases/tag/v2.11.43
https://github.com/traefik/traefik/releases/tag/v2.11.43
https://github.com/traefik/traefik/releases/tag/v3.6.14
https://github.com/traefik/traefik/releases/tag/v3.6.14
https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2
https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2
https://github.com/traefik/traefik/security/advisories/GHSA…
https://github.com/traefik/traefik/security/advisories/GHSA-5m6w-wvh7-57vm