CVE-2026-57209 — Heimdall: Forwarded Header Injection via Unsanitized Host Header in Proxy Mode
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 …
Published: 2026-10-23 · CVSS: 7.0 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7