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CVE-2026-33433

8.8 · HIGH

Traefik is an HTTP reverse proxy and load balancer.

Published Mar 27, 2026CWE-290EPSS 0.56%

Overview

CVE-2026-33433 is a high-severity vulnerability. It was published on March 27, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/traefik/traefik/releases/tag/v2.11.42GitHubgithub.com/traefik/traefik/releases/tag/v3.6.11GitHubgithub.com/traefik/traefik/releases/tag/v3.7.0-ea.3GitHubgithub.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7cRefaccess.redhat.com/errata/RHSA-2026:10175Refaccess.redhat.com/security/cve/CVE-2026-33433Refbugzilla.redhat.com/show_bug.cgi?id=2452289Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33433.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-33433?

CVE-2026-33433 is a high-severity vulnerability. It was published on March 27, 2026 and has a CVSS 3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-33433?

This vulnerability has a CVSS 3.1 base score of 8.8, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-33433?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-33433?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-33433 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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