{"schema":"threatline.record/2","record":{"id":"CVE-2026-84747","aliases":[],"summary":"Apache bRPC: Access Control Bypass via HTTP Request Paths Containing Empty Path Segments","details":"Interpretation conflict in the HTTP protocol implementation in Apache bRPC (version < 1.18.0) on all platforms allows remote attackers to bypass access control rules enforced by a front proxy.\n\nRoot Cause:\nThe method dispatch function FindMethodPropertyByURI() in bRPC's HTTP protocol splits the request path with a string splitter that skips empty fields, so paths containing empty path segments (consecutive slashes), such as //flags, /flags// and /flags//port, are dispatched to the same method as their collapsed form /flags. Per RFC 3986 these are distinct paths. A front proxy that enforces an ACL (e.g. blocking access to builtin services such as /flags) matches the collapsed form only, and therefore forwards the padded literal to the bRPC server, where it is dispatched as if it were the collapsed form. This differential allows //flags?setvalue= to reach a builtin service that /flags is not allowed to reach. Additionally, the HTTP/2 implementation never validated the :path pseudo-header, so requests without a :path, or with a :path that neither begins with '/' nor is the asterisk-form '*', contrary to RFC 9113 section 8.3.1, were not rejected.\n\nAffected Scenarios:\nDeployments of Apache bRPC behind a front proxy or gateway that performs access control (ACL) decisions on the literal request path, where the bRPC server accepts HTTP or HTTP/2 traffic from that proxy. In such deployments an attacker can send a path containing empty path segments to reach a resource that the front proxy intended to block.\n\nHow to Fix:\n(Choose one of the following options)\n1. Upgrade bRPC to version 1.18.0, which fixes this issue.\n2. Apply this patch:  https://github.com/apache/brpc/pull/3512 \n\nNote:\nAfter applying the fix, HTTP and HTTP/2 request paths containing empty path segments (consecutive slashes) are rejected by default, and HTTP/2 :path values that are empty or neither begin with '/' nor equal '*' are rejected. Deployments that depend on the previous lenient behavior can restore it by turning on the gflag -http_allow_empty_path_segments, which is not recommended for servers exposed to untrusted traffic.","categories":["Frameworks"],"product":"Apache bRPC","vendor":"Apache Software Foundation","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84747","source_modified_at":"2026-10-21T12:13:28.033Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Apache bRPC","vendor":"Apache Software Foundation","versions":[{"status":"affected","version":"0","lessThan":"1.18.0","versionType":"semver"}],"defaultStatus":"unaffected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-84747","source_modified_at":"2026-10-21T12:13:28.033Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Apache bRPC","ecosystem":null},"version":"1.18.0","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.00215,"percentile":0.11359,"score_date":"2026-10-23"},"published_at":"2026-10-21T12:13:28.033Z","modified_at":"2026-10-21T12:13:28.033Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-84747","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-21T12:13:28.033Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-84747","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb","tags":["vendor-advisory"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-21T12:13:28.033Z","content_hash":"e284730dcf5ad823fa1e35f77aef693e6bdad7d3787b9ece94ebd76b05bf2bcb"}}