CVE Catalog

CVE-2026-84747

Low risk· EPSS 11%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.22%

11th percentile - higher than 11% of all known CVEs

Summary

A vulnerability in Apache bRPC (versions < 1.18.0) stems from an interpretation conflict in HTTP path handling between bRPC and a front proxy. The FindMethodPropertyByURI() function skips empty path segments (consecutive slashes), so paths like //flags are dispatched as /flags, even though RFC 3986 treats them as distinct. Additionally, HTTP/2 does not validate the :path pseudo-header, allowing bypass of proxy ACL rules and access to internal services.

Risk Assessment

An attacker can bypass front proxy access control and reach restricted built-in bRPC services such as /flags, potentially leading to unauthorized configuration changes or information disclosure.

Recommendation

Upgrade Apache bRPC to version 1.18.0 or apply the patch from PR #3512. Do not enable the -http_allow_empty_path_segments flag on servers exposed to untrusted traffic.

Other vulnerabilities in Apache bRPC

See all
Original NVD description (English source)

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. Root Cause: The 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. Affected Scenarios: Deployments 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. How to Fix: (Choose one of the following options) 1. Upgrade bRPC to version 1.18.0, which fixes this issue. 2. Apply this patch: https://github.com/apache/brpc/pull/3512 Note: After 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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS