CVE•Published 2026-03-27•Modified 2026-06-30•1 article on news•6 live references•NVD data

CVE-2026-33433Traefik · Traefik

Vulnerability data via NVD (ingested)

CVSS v3.1

8.8

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS percentile

—

Weaknesses (CWE)

CWE-290Authentication Bypass by Spoofing

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.

Timeline

Published 2026-03-27

Modified 2026-06-30

External references

NVD MITRE Exploit-DB GitHub PoC Sploitus VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-33433

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Traefik Traefik"

All exposed Traefik Traefik instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"Traefik"

HTTP body or banner mentions "Traefik" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-33433