Traefik: lowercase `Connection` tokens can delete traefik-managed forwarded identity headers (for example, `X-Real-Ip`)

{
  "id": "fb9d4631ce6aaa9067c55bc9a67b727d26064ebaf59c062fbdea4c164ac534fc",
  "url": "https://osv.dev/vulnerability/CVE-2026-29054",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Traefik: lowercase `Connection` tokens can delete traefik-managed forwarded identity headers (for example, `X-Real-Ip`)",
    "summary": "Traefik is an HTTP reverse proxy and load balancer. From version 2.11.9 to 2.11.37 and from version 3.1.3 to 3.6.8, there is a potential vulnerability in Traefik managing the Connection header with X-Forwarded headers. When Traefik processes HTTP/1.1 requests, the protection put in place to prevent the removal of Traefik-managed X-Forwarded headers (such as X-Real-Ip, X-Forwarded-Host, X-Forwarded-Port, etc.) via the Connection header does not handle case sensitivity correctly. The Connection tokens are compared case-sensitively against the protected header names, but the actual header deletion operates case-insensitively. As a result, a remote unauthenticated client can use lowercase Connection tokens (e.g. Connection: x-real-ip) to bypass the protection and trigger the removal of Traefik-managed forwarded identity headers. This issue has been patched in versions 2.11.38 and 3.6.9.",
    "evidence": "osv:CVE-2026-29054",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-29054",
      "aliases": [
        "CVE-2026-29054",
        "GHSA-92mv-8f8w-wq52",
        "GO-2026-4597"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/traefik/traefik",
              "type": "GIT",
              "events": [
                {
                  "introduced": "06d7fab820dc1e486fe59371aeb359c965767ded"
                },
                {
                  "fixed": "7c55452b21e7465d95bd731725c7222f7626265b"
                },
                {
                  "introduced": "89f3b272c3d4ed3f075f92f8acca494cdba4f708"
                },
                {
                  "fixed": "65f9d0663202b0ebf7941da0c4af0f1953525ce6"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "2.11.9"
                      },
                      {
                        "fixed": "2.11.38"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "3.1.3"
                      },
                      {
                        "fixed": "3.6.9"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "7c55452b21e7465d95bd731725c7222f7626265b"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v2.11.38"
                  },
                  {
                    "range": [
                      {
                        "fixed": "65f9d0663202b0ebf7941da0c4af0f1953525ce6"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v3.6.9"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.11.37",
            "v2.11.36",
            "v2.11.35",
            "v2.11.34",
            "v2.11.33",
            "v2.11.32",
            "v2.11.31",
            "v2.11.30",
            "v2.11.29",
            "v2.11.28",
            "v2.11.27",
            "v2.11.26",
            "v2.11.25",
            "v2.11.24",
            "v2.11.23",
            "v2.11.22",
            "v2.11.21",
            "v2.11.20",
            "v2.11.19",
            "v2.11.18",
            "v2.11.17",
            "v2.11.16",
            "v2.11.15",
            "v2.11.14",
            "v2.11.13",
            "v2.11.12",
            "v2.11.11",
            "v2.11.10",
            "v2.11.9"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-29054.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.213531509Z",
      "provider": "osv",
      "references": [
        "https://github.com/traefik/traefik/releases/tag/v2.11.38",
        "https://github.com/traefik/traefik/releases/tag/v3.6.9",
        "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-29054.json",
        "https://access.redhat.com/errata/RHSA-2026:10175",
        "https://access.redhat.com/security/cve/CVE-2026-29054",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/29xxx/CVE-2026-29054.json",
        "https://github.com/traefik/traefik/security/advisories/GHSA-92mv-8f8w-wq52",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-29054",
        "https://bugzilla.redhat.com/show_bug.cgi?id=2444872"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-178"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/29xxx/CVE-2026-29054.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-29054",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492805,
  "published_at": "2026-03-05T16:18:49.23+00:00"
}