{"id":"CVE-2026-42274","aliases":["GHSA-3q34-rx83-r6mq","GO-2026-5097"],"url":"https://o3.security/vulnerability/CVE-2026-42274","summary":"Heimdall: Authorization bypass via path normalization mismatch","details":"### Summary\n\nHeimdall 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](https://www.rfc-editor.org/rfc/rfc3986#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`).\n\n### Details\n\nThis vulnerability can be exploited by an adversary if rule matching is performed using free (named or unnamed) wildcards without further constraints, as shown in the example snippets below.\n\n```yaml\nid: rule-1\nmatch:\n  routes:\n    - path: /user/**\nexecute: # configured to require authentication and authorization\n  # ...\n```\n\n```yaml\nid: rule-2\nmatch:\n  routes:\n    - path: /public/**\nexecute: # configured to allow anonymous access\n  # ...\n```\n\nIf an adversary sends a request to `/public/../user/whatever`, rule-2 will be matched and executed. The downstream service may, however, normalize the request path and interpret it as `/user/whatever`.\n\n### Impact\n\nBypass of access control policies enforced by heimdall may lead to the following consequences:\n\n* Access to or modification of data that should be restricted\n* Invocation of functionality that is expected to require authentication or authorization\n* In certain configurations, escalation of privileges depending on the exposed functionality\n\n### Workarounds\n\n* Normalize HTTP paths or reject HTTP paths containing relative path expressions in the layers in front of Heimdall - this is good practice anyway. Some proxies do that by default, such as Traefik; others, such as Envoy, require additional configuration (for Envoy see [`normalize_path`](https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/filters/network/http_connection_manager/v3/http_connection_manager.proto#envoy-v3-api-field-extensions-filters-network-http-connection-manager-v3-httpconnectionmanager-normalize-path)).\n* Include the ID of the rule expected to be executed in the JWT issued by heimdall and check that value in the consuming project's service.","published":"2026-05-08T03:43:41.597Z","modified":"2026-10-28T02:30:41.617815302Z","cvss":null,"epss":{"score":0.00368,"percentile":0.30485,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/dadrus/heimdall","fixedVersion":"0.17.14"}],"fix":{"url":"https://github.com/dadrus/heimdall/commit/b5dfa484b7a8c2ce6d8691c026f9da867719947a","label":"dadrus/heimdall@b5dfa48"},"references":[{"type":"WEB","url":"https://github.com/dadrus/heimdall/releases/tag/v0.17.14"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42274.json"},{"type":"ADVISORY","url":"https://github.com/dadrus/heimdall/security/advisories/GHSA-3q34-rx83-r6mq"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42274"},{"type":"FIX","url":"https://github.com/dadrus/heimdall/commit/b5dfa484b7a8c2ce6d8691c026f9da867719947a"},{"type":"FIX","url":"https://github.com/dadrus/heimdall/pull/3209"},{"type":"PACKAGE","url":"https://github.com/dadrus/heimdall"},{"type":"WEB","url":"https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/filters/network/http_connection_manager/v3/http_connection_manager.proto#envoy-v3-api-field-extensions-filters-network-http-connection-manager-v3-httpconnectionmanager-normalize-path"},{"type":"WEB","url":"https://www.rfc-editor.org/rfc/rfc3986#section-6.2.2.3"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:30:41.617815302Z"}}