Is CVE-2026-33433 actively exploited?

No active exploitation of CVE-2026-33433 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-33433 be exploited remotely?

Yes. CVE-2026-33433 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-33433?

CVE-2026-33433 has a CVSS score of 5.1 (MEDIUM).

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MEDIUM

CVE-2026-33433

CWE-290Published: March 27, 2026· Updated: Mar 30, 2026

5.1

CVSS v3.1

EPSS:0.01%probability of exploitation in 30 daysPercentile:1.3th

Official 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.

NVD Source

Technical Analysis

CVE-2026-33433 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires high privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges Req.High

User InteractionNone

ScopeX

Impact

Confidentiality

Integrity

Availability

CVSS:4.0/AV:N/AC:H/AT:P/PR:H/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