Live › vulnerability › CVE-2026-57210
Go to dashboardWhen trusted_proxies is configured, Heimdall takes client IP addresses from Forwarded and X-Forwarded-For headers without checking they are valid IPs, and mis-parses quoted Forwarded values. Rules that trust these addresses can be fooled into accepting attacker-chosen client IPs.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Only Heimdall deployments before 0.17.17 that set the trusted_proxies option and use rules that depend on client IP addresses are exposed, because those rules receive the header-supplied addresses. Deployments without trusted_proxies, or whose rules do not check client IPs, are not affected by the header parsing problem.
No product ranges from the sources yet.
heimdall version or the image tag, and compare it to 0.17.17trusted_proxies in the Heimdall configuration file; the issue only applies when it is set0.17.17 or latertrusted_proxies if not needed, or restrict rules that depend on client IP addressesEach row is the first time that source carried this signal. The analyst’s rows are its own findings.
Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.17, when the trusted_proxies option is configured, heimdall extracts client IP addresses from the Forwarded (for= parameter) and X-Forwarded-For headers and exposes them as Request.ClientIPAddresses to the rule pipeline. However, extracted values are not validated to be syntactically valid IP addresses. Arbitrary strings, malformed IP literals, and RFC 7239 unknown values and obfuscated identifiers are accepted without further checks. In addition, the Forwarded header parser splits on , and ; without accounting for RFC 7239 quoted strings, which can cause a single quoted value to be parsed as multiple entries, with fragments — including trailing quote characters — treated as independent addresses. This issue has been patched in version 0.17.17.
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