CVE Tools
Sign in

CVE-2026-33433

Traefik Vulnerable to BasicAuth/DigestAuth Identity Spoofing via Non-Canonical headerField

Published: Mar 27, 2026Updated: Apr 3, 2026 Sources: CVE List NVD BDUCWE-290
NVD MITRE
8.8CVSSHIGH
EPSS Score
0.4%
Top 64.3%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.42, 3.6.11, and 3.7.0-ea.3, when `headerField` is configured with a non-canonical HTTP header name (e.g., `x-auth-user` instead of `X-Auth-User`), an authenticated attacker can inject their own canonical version of that header to impersonate any identity to the backend. The backend receives two header entries — the attacker-injected canonical one is read first, overriding Traefik's non-canonical write. Versions 2.11.42, 3.6.11, and 3.7.0-ea.3 patch the issue.

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-290

Affected Products

traefiktraefik
On-prem
Networking Infrastructure / load-balancer-proxy
TraefikContainous
On-prem
Networking Infrastructure / load-balancer-proxy
OpenShift Dev SpacesRed Hat Inc.
SaaSSaaS Service
Cloud & SaaS / container-orchestration
traefikoss-projectNetworking Infrastructureaka traefik enterprise
containousoss-projectFRNetworking Infrastructureaka containous
red hat inc.commercialUSOperating Systemsaka red hat

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Initial Access
View detailed technique mapping

References

https://github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c
github.com
https://github.com/traefik/traefik/releases/tag/v2.11.42
github.com
https://github.com/traefik/traefik/releases/tag/v3.6.11
github.com
and 3 more references View all →

Timeline

Published
Mar 27, 2026
Last Updated
Apr 3, 2026

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2026-33433 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows