CVE-2026-57209
High
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.
SeverityHigh
CVSS7.0
Exploit probability42. percentile0.5%
ProductGithub.com/dadrus/heimdall
PublishedOct 23, 2026
First seenOct 23, 2026
Weakness typeCWE-20Improper input validationCWE-74Injection
How to fix
Update
- github.com/dadrus/heimdall0.17.17 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| github.com/dadrus/heimdallGo | v < 0.17.17 | 0.17.17 |
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