CVE-2026-33433

HIGHNVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.8 under NVD CVSS v3. EPSS exploit probability: 0.0%, top 92% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
8.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 8.8Exploit: NoneExposed: 0

A fix is available — apply it.

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 v3
8.8
EG Score
8.8(medium)
EPSS
37.9%
KEV
Not listed

Published

March 27, 2026

Last Modified

July 15, 2026

Advisory Details (4)

Auto-updated May 22, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

BasicAuth/DigestAuth Identity Spoofing via Non-Canonical headerField · Advisory · traefik/traefik · GitHub

https://github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c
generic

Release v3.7.0-ea.3 · traefik/traefik · GitHub

https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3
generic

Release v3.6.11 · traefik/traefik · GitHub

https://github.com/traefik/traefik/releases/tag/v3.6.11
generic

Release v2.11.42 · traefik/traefik · GitHub

https://github.com/traefik/traefik/releases/tag/v2.11.42

Vendor Advisories for CVE-2026-33433(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatdevspaces/traefik-rhel9:17767185852026-04-23redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(3 across 1 ecosystem)
Go(3)
PackageVulnerable rangeFixed inDependents
github.com/traefik/traefik———
github.com/traefik/traefik/v2—2.11.42—
github.com/traefik/traefik/v3—3.7.0-ea.3—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 43× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 108 total refreshes for this CVE.

  1. 2026-07-22 14:08 UTCEPSS rescore
  2. 2026-07-21 15:24 UTCEPSS rescore
  3. 2026-07-20 17:08 UTCEPSS rescore
  4. 2026-07-19 14:31 UTCEPSS rescore
  5. 2026-07-19 02:29 UTCEPSS rescore
  6. 2026-07-18 10:04 UTCEPSS rescore
  7. 2026-07-17 05:24 UTCOSV refresh
  8. 2026-07-16 17:03 UTCEPSS rescore
  9. 2026-07-15 16:57 UTCEPSS rescore
  10. 2026-07-15 16:57 UTCEPSS rescore
  11. 2026-07-15 02:22 UTCNVD updateCVSS v3 → 8.8
  12. 2026-07-15 02:00 UTCEPSS rescore
  13. 2026-07-15 02:00 UTCEPSS rescore
  14. 2026-07-15 01:21 UTCMITRE cvelistV5CVSS v3 → 7.7
  15. 2026-07-13 22:30 UTCEPSS rescore
  16. 2026-07-13 06:13 UTCEPSS rescore
  17. 2026-07-13 06:13 UTCEPSS rescore
  18. 2026-07-12 05:46 UTCEPSS rescore
  19. 2026-07-11 08:27 UTCEPSS rescore
  20. 2026-07-09 19:10 UTCEPSS rescore
  21. 2026-07-08 15:15 UTCEPSS rescore
  22. 2026-07-07 13:46 UTCEPSS rescore
  23. 2026-07-06 16:27 UTCEPSS rescore
  24. 2026-07-06 16:27 UTCEPSS rescore
  25. 2026-07-06 02:23 UTCEPSS rescore
Show 75 more
  1. 2026-07-06 02:23 UTCEPSS rescore
  2. 2026-07-05 02:30 UTCEPSS rescore
  3. 2026-07-04 06:31 UTCEPSS rescore
  4. 2026-07-01 15:06 UTCEPSS rescore
  5. 2026-06-30 23:22 UTCEPSS rescore
  6. 2026-06-29 14:06 UTCEPSS rescore
  7. 2026-06-29 14:06 UTCEPSS rescore
  8. 2026-06-29 03:32 UTCOSV refresh
  9. 2026-06-28 14:07 UTCEPSS rescore
  10. 2026-06-28 14:07 UTCEPSS rescore
  11. 2026-06-28 04:56 UTCEPSS rescore
  12. 2026-06-28 04:56 UTCEPSS rescore
  13. 2026-06-27 03:08 UTCEPSS rescore
  14. 2026-06-25 13:49 UTCEPSS rescore
  15. 2026-06-25 13:49 UTCEPSS rescore
  16. 2026-06-24 14:05 UTCEPSS rescore
  17. 2026-06-23 21:33 UTCEPSS rescore
  18. 2026-06-23 21:33 UTCEPSS rescore
  19. 2026-06-22 14:25 UTCEPSS rescore
  20. 2026-06-22 14:25 UTCEPSS rescore
  21. 2026-06-21 14:56 UTCEPSS rescore
  22. 2026-06-21 14:56 UTCEPSS rescore
  23. 2026-06-21 01:59 UTCEPSS rescore
  24. 2026-06-19 19:25 UTCEPSS rescore
  25. 2026-06-19 19:25 UTCEPSS rescore
  26. 2026-06-18 17:52 UTCEPSS rescore
  27. 2026-06-18 17:52 UTCEPSS rescore
  28. 2026-06-17 17:53 UTCEPSS rescore
  29. 2026-06-16 17:52 UTCEPSS rescore
  30. 2026-06-15 17:49 UTCEPSS rescore
  31. 2026-06-13 23:00 UTCEPSS rescore
  32. 2026-06-12 23:12 UTCEPSS rescore
  33. 2026-06-12 23:12 UTCEPSS rescore
  34. 2026-06-11 23:02 UTCVendor advisory
  35. 2026-06-11 14:00 UTCEPSS rescore
  36. 2026-06-10 22:18 UTCEPSS rescore
  37. 2026-06-10 14:44 UTCVendor advisory
  38. 2026-06-10 13:22 UTCEPSS rescore
  39. 2026-06-10 02:45 UTCVendor advisory
  40. 2026-06-09 15:26 UTCVendor advisory
  41. 2026-06-08 14:17 UTCEPSS rescore
  42. 2026-06-08 14:17 UTCEPSS rescore
  43. 2026-06-08 13:16 UTCVendor advisory
  44. 2026-06-07 23:20 UTCVendor advisory
  45. 2026-06-07 15:25 UTCEPSS rescore
  46. 2026-06-07 15:25 UTCEPSS rescore
  47. 2026-06-07 15:25 UTCEPSS rescore
  48. 2026-06-07 11:56 UTCVendor advisory
  49. 2026-06-06 13:47 UTCEPSS rescore
  50. 2026-06-06 13:47 UTCEPSS rescore
  51. 2026-06-05 22:47 UTCEPSS rescore
  52. 2026-06-05 22:47 UTCEPSS rescore
  53. 2026-06-05 06:10 UTCEPSS rescore
  54. 2026-06-05 06:10 UTCEPSS rescore
  55. 2026-06-04 13:12 UTCEPSS rescore
  56. 2026-06-04 13:12 UTCEPSS rescore
  57. 2026-06-02 20:13 UTCEPSS rescore
  58. 2026-06-01 13:52 UTCEPSS rescore
  59. 2026-06-01 13:52 UTCEPSS rescore
  60. 2026-06-01 13:51 UTCEPSS rescore
  61. 2026-06-01 06:13 UTCOSV refresh
  62. 2026-05-31 22:30 UTCEPSS rescore
  63. 2026-05-31 22:30 UTCEPSS rescore
  64. 2026-05-31 00:16 UTCEPSS rescore
  65. 2026-05-31 00:16 UTCEPSS rescore
  66. 2026-05-31 00:16 UTCEPSS rescore
  67. 2026-05-29 13:44 UTCEPSS rescore
  68. 2026-05-29 13:44 UTCEPSS rescore
  69. 2026-05-28 13:44 UTCEPSS rescore
  70. 2026-05-28 13:44 UTCEPSS rescore
  71. 2026-05-28 13:44 UTCEPSS rescore
  72. 2026-05-27 13:40 UTCEPSS rescore
  73. 2026-05-27 13:40 UTCEPSS rescore
  74. 2026-05-27 13:40 UTCEPSS rescore
  75. 2026-05-26 13:44 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-33433?
CVE-2026-33433 is a high vulnerability published on March 27, 2026. 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…
When was CVE-2026-33433 disclosed?
CVE-2026-33433 was first published in the National Vulnerability Database on March 27, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33433 actively exploited?
CVE-2026-33433 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 37.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-33433?
CVE-2026-33433 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-33433?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33433, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-33433

Explore →

Is Your Infrastructure Affected by CVE-2026-33433?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs