{"id":"CVE-2026-33433","state":"PUBLISHED","title":"Traefik Vulnerable to BasicAuth/DigestAuth Identity Spoofing via Non-Canonical headerField","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.","publishedAt":"2026-03-27T13:49:08.455Z","updatedAt":"2026-07-15T01:06:25.616Z","severity":{"score":5.1,"label":"Medium","version":"4.0","vector":"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","source":"GitHub_M"},"assigner":"GitHub_M","products":["traefik traefik"],"affected":[{"vendor":"traefik","product":"traefik","versions":[{"version":"< 2.11.42","status":"affected"},{"version":">= 3.0.0-beta1, < 3.6.11","status":"affected"},{"version":">= 3.7.0-ea.1, < 3.7.0-ea.3","status":"affected"}]}],"references":["https://github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c","https://github.com/traefik/traefik/releases/tag/v2.11.42","https://github.com/traefik/traefik/releases/tag/v3.6.11","https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3","https://access.redhat.com/security/cve/CVE-2026-33433","https://bugzilla.redhat.com/show_bug.cgi?id=2452289","https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33433.json","https://access.redhat.com/errata/RHSA-2026:10175"],"weaknesses":["CWE-290"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/33xxx/CVE-2026-33433.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33433","state":"PUBLISHED","datePublished":"2026-03-27T13:49:08.455Z","dateUpdated":"2026-07-15T01:06:25.616Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-03-19T18:45:22.436Z"},"containers":{"cna":{"title":"Traefik Vulnerable to BasicAuth/DigestAuth Identity Spoofing via Non-Canonical headerField","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"traefik","product":"traefik","versions":[{"version":"< 2.11.42","status":"affected"},{"version":">= 3.0.0-beta1, < 3.6.11","status":"affected"},{"version":">= 3.7.0-ea.1, < 3.7.0-ea.3","status":"affected"}]}],"references":[{"url":"https://github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c","name":"https://github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/traefik/traefik/releases/tag/v2.11.42","name":"https://github.com/traefik/traefik/releases/tag/v2.11.42","tags":["x_refsource_MISC"]},{"url":"https://github.com/traefik/traefik/releases/tag/v3.6.11","name":"https://github.com/traefik/traefik/releases/tag/v3.6.11","tags":["x_refsource_MISC"]},{"url":"https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3","name":"https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"HIGH","attackRequirements":"PRESENT","privilegesRequired":"HIGH","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"HIGH","subIntegrityImpact":"HIGH","subAvailabilityImpact":"NONE","baseScore":5.1,"baseSeverity":"MEDIUM","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-290","lang":"en","description":"CWE-290: Authentication Bypass by Spoofing","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-03-27T13:49:08.455Z"},"source":{"advisory":"GHSA-qr99-7898-vr7c","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-30T12:00:28.784939Z","id":"CVE-2026-33433","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-03-30T12:00:41.940Z"}},{"title":"github.com/traefik/traefik: Traefik: Authentication bypass via non-canonical HTTP header injection","descriptions":[{"lang":"en","value":"A flaw was found in Traefik, an HTTP reverse proxy and load balancer. When the `headerField` is configured with a non-canonical HTTP header name, an authenticated attacker can inject a canonical version of that header. This allows the attacker to impersonate any identity to the backend, leading to an authentication bypass. The backend prioritizes the attacker-injected header, overriding Traefik's intended header."}],"affected":[{"vendor":"Red Hat","product":"Red Hat OpenShift Dev Spaces 3.27","packageName":"devspaces/traefik-rhel9","defaultStatus":"affected","versions":[{"version":"1776718585","status":"unaffected","lessThan":"*","versionType":"rpm"}],"collectionURL":"https://catalog.redhat.com/software/containers/","cpes":["cpe:/a:redhat:openshift_devspaces:3.27::el9"]}],"references":[{"url":"https://access.redhat.com/security/cve/CVE-2026-33433","tags":["vdb-entry","x_refsource_REDHAT"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2452289","name":"RHBZ#2452289","tags":["issue-tracking","x_refsource_REDHAT"]},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33433.json","tags":["x_sadp-csaf-vex"]},{"url":"https://access.redhat.com/errata/RHSA-2026:10175","tags":["vendor-advisory","x_refsource_REDHAT"]}],"metrics":[{"other":{"content":{"namespace":"https://access.redhat.com/security/updates/classification/","value":"Important"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":7.7,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"HIGH","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:N","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-290","description":"Authentication Bypass by Spoofing","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"redhat-SADP","orgId":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c","dateUpdated":"2026-07-15T01:06:25.616Z"},"datePublic":"2026-03-27T13:49:08.455Z","solutions":[{"lang":"en","value":"RHSA-2026:10175: Red Hat OpenShift Dev Spaces 3.27"}],"timeline":[{"lang":"en","time":"2026-03-27T15:03:19.672Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-03-27T13:49:08.455Z","value":"Made public."}],"workarounds":[{"lang":"en","value":"Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."}],"x_adpType":"supplier","x_generator":{"engine":"sadp-cli 1.0.0"}}]}}}