What’s Vulnerable › Vulnerabilities

CVE-2026-57209: Heimdall: Forwarded Header Injection via Unsanitized Host Header in Proxy Mode

• Severity: high (CVSS 7.0 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-23 · updated 2026-10-29
• Weakness: CWE-20

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.

Affected products

• dadrus heimdall: before 0.17.17

References

• https://github.com/dadrus/heimdall/releases/tag/v0.17.17
• https://github.com/dadrus/heimdall/security/advisories/GHSA-4jgr-pg2m-m988
• https://github.com/dadrus/heimdall/security/advisories/GHSA-4jgr-pg2m-m988

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