CVE-2026-57209

Heimdall: Forwarded Header Injection via Unsanitized Host Header in Proxy Mode

Published Oct 23, 2026 CVSS 4.0 · 7 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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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
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Dadrus
Dadrus heimdall
Vendors & Products Dadrus
Dadrus heimdall
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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Oct 29, 2026, 1:16 PM
Reserved
Jun 24, 2026, 2:00 AM
Status
Deferred
Published
Oct 23, 2026, 1:17 PM
Modified
Oct 29, 2026, 2:17 PM