Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.17, when Heimdall operates in proxy mode, it constructs the Forwarded HTTP header after executing the matched rule pipeline by inserting the incoming request's Host header value directly into the header string without sanitizing commas or semicolons. This allows an attacker to inject additional parameters into the Forwarded header, potentially spoofing IP addresses for upstream services. This issue has been patched in version 0.17.17.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-4jgr-pg2m-m988 Heimdall: Forwarded Header Injection via Unsanitized Host Header in Proxy Mode
Fixes

Solution

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Workaround

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History

Fri, 23 Oct 2026 12:45:00 +0000

Type Values Removed Values Added
Description Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.17, when Heimdall operates in proxy mode, it constructs the Forwarded HTTP header after executing the matched rule pipeline by inserting the incoming request's Host header value directly into the header string without sanitizing commas or semicolons. This allows an attacker to inject additional parameters into the Forwarded header, potentially spoofing IP addresses for upstream services. This issue has been patched in version 0.17.17.
Title Heimdall: Forwarded Header Injection via Unsanitized Host Header in Proxy Mode
Weaknesses CWE-20
CWE-74
References
Metrics cvssV4_0

{'score': 7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-23T12:27:19.621Z

Reserved: 2026-06-24T02:00:46.801Z

Link: CVE-2026-57209

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-23T13:17:11.687

Modified: 2026-10-23T13:17:11.687

Link: CVE-2026-57209

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

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Weaknesses