{"id":"CVE-2021-32813","aliases":["GHSA-m697-4v8f-55qg","GO-2022-0923"],"title":"Header dropping in traefik","summary":"Header dropping in traefik","severity":"medium","cvss":4.8,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","vendor":"traefik","product":"github.com/traefik/traefik/v2","ecosystem":"go","affected":["github.com/traefik/traefik/v2 < 2.4.13","github.com/traefik/traefik <= 1.7.30"],"patched":["github.com/traefik/traefik/v2 2.4.13"],"published":"2021-08-05","updated":"2026-07-08","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-m697-4v8f-55qg","references":[{"url":"https://github.com/traefik/traefik/security/advisories/GHSA-m697-4v8f-55qg"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-32813"},{"url":"https://github.com/traefik/traefik/pull/8319/commits/cbaf86a93014a969b8accf39301932c17d0d73f9"},{"url":"https://github.com/traefik/traefik/releases/tag/v2.4.13"},{"url":"github.com/traefik/traefik"}],"tags":["osv","go"],"epss":0.011,"epssPercentile":0.6425,"ingestedAt":"2026-07-09T18:56:36.611Z","slug":"CVE-2021-32813","body":"## Overview\n\n# Impact\n\nThere exists a potential header vulnerability in Traefik's handling of the Connection header. Active exploitation of this issue is unlikely, as it requires that a removed header would lead to a privilege escalation, however, the Traefik team has addressed this issue to prevent any potential abuse.\n\n# Details\n\nIf you have a chain of Traefik middlewares, and one of them sets a request header `Important-Security-Header`, then sending a request with the following Connection header will cause it to be removed before the request was sent:\n\n```\ncurl 'https://example.com' -H \"Connection: Important-Security-Header\" -0\n```\n\nIn this case, the backend does not see the request header `Important-Security-Header`.\n\n# Patches\n\nTraefik v2.4.x: https://github.com/traefik/traefik/releases/tag/v2.4.13\n\n# Workarounds\n\nNo.\n\n# For more information\n\nIf you have any questions or comments about this advisory, [open an issue](https://github.com/traefik/traefik/issues).\n\n\n## Affected packages\n\n- `github.com/traefik/traefik/v2 < 2.4.13`\n- `github.com/traefik/traefik <= 1.7.30`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `github.com/traefik/traefik/v2 2.4.13`","depth":"sunlit","depthScore":27,"depthScoreParts":{"impact":26.4,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}