Threat database

Heimdall versions prior to 0.17.17 improperly validate client IP addresses extracted from Forwarded and X-Forwarded-For headers when the trusted_proxies option is enabled. This allows arbitrary, malformed, or obfuscated IP values to be accepted and processed. The Forwarded header parser also incorrectly splits quoted strings, causing parsing errors. This vulnerability has been fixed in version 0.17.17.

Heimdall versions prior to 0.17.17 have an improper input validation vulnerability in proxy mode. The software constructs the Forwarded HTTP header by directly inserting the incoming request's Host header without sanitizing commas or semicolons. This allows attackers to inject additional parameters into the Forwarded header, potentially spoofing IP addresses for upstream services. The issue is patched in version 0.17.17.

linuxserver Heimdall through 2.8.3 applies its SafeUrlFetcher SSRF protection mechanism only to ItemController; the enhanced-application test and live-stats requests occur via SupportedApps::execute(), a GuzzleHttp client that lacks IP address restrictions. In some realistic installations, the POST /test_config (and GET /get_stats) endpoints are accessible through CSRF, and thus an unauthenticated attacker can force the server to send requests to arbitrary internal hosts and ports (including 169.254.169.254) and read a status/port oracle in addition to partial response data.

Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall performs rule matching on the raw (non-normalized) request path, while downstream components may normalize dot-segments according to RFC 3986, Section 6.2.2.3. This discrepancy can result in heimdall authorizing a request for one path (e.g., /user/../admin, or URL-encoded variants such as /user/%2e%2e/admin or /user/%2e%2e%2fadmin. The latter would require the allow_encoded_slashes option to be set to on or no_decode.) while the downstream ultimately processes a different, normalized path (/admin). This issue has been patched in version 0.17.14.

CVE-2026-42273 is a high-severity vulnerability in dadrus heimdall, a cloud native Identity Aware Proxy and Access Control Decision service. The issue arises because heimdall versions prior to 0.17.14 perform host matching in a case-sensitive manner, whereas HTTP hostnames are case-insensitive by standard. This mismatch can cause heimdall to fail to match rules correctly when the request host differs only in letter casing, potentially leading to unintended request classification. The vulnerability has been addressed in version 0.17.14.

CVE-2026-42272 is a vulnerability in dadrus heimdall, a cloud native Identity Aware Proxy and Access Control Decision service. Versions prior to 0.17.14 handle URL-encoded slashes (%2F) in a case-sensitive way, contrary to the case-insensitive definition of percent-encoding. This causes the lowercase equivalent (%2f) to be unrecognized and improperly processed when the default setting allow_encoded_slashes is off. This discrepancy can lead to differences in request path interpretation between heimdall and upstream components, potentially allowing authorization bypass. The issue has been fixed in version 0.17.14. The vulnerability has a CVSS 4.

LinuxServer.io Heimdall before 2.7.3 allows XSS via the q parameter.

An issue in Linux Server Heimdall v.2.6.1 allows a remote attacker to execute arbitrary code via a crafted script to the Add new application.