Apache bRPC: Out-of-bounds read via non-object fields in Discovery naming-service reply parsing

{
  "id": "8f41c37a7cec9ca51c55eadd8506258a9de15f27cf7560a9cffa04dfa449f33f",
  "url": "https://osv.dev/vulnerability/CVE-2026-87849",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Apache bRPC: Out-of-bounds read via non-object fields in Discovery naming-service reply parsing",
    "summary": "The Discovery naming-service reply parser in Apache bRPC (versions < 1.18.0) calls RapidJSON object-only accessors (FindMember) on JSON values without first validating that those values are objects. A malformed Discovery response whose data/service members or instances list contain non-object entries (e.g. a bare integer) triggers the RapidJSON object-access precondition on the client, reading memory out of bounds and potentially crashing the bRPC client. Root Cause: In src/brpc/policy/discovery_naming_service.cpp, DiscoveryNamingService::GetServers() and DiscoveryNames::ListDiscoveryNodes() access JSON values with member functions on non-object values. RapidJSON only defines these operations for object types; invoking them on a non-object violates the class invariant and results in undefined behavior (out-of-bounds read), commonly crashing the process. Affected Scenarios: An operator-configured (or compromised) Discovery backend returns a malformed /discovery/nodes or /discovery/fetchs response whose data/service/instance entries are not JSON objects, crashing any bRPC client that refreshes its server list. How to Fix: 1. Upgrade bRPC to version 1.18.0 or later, which fixes this issue. 2. Apply this patch: https://github.com/apache/brpc/pull/3533 The fix validates that the Discovery response data, per-service data, and instance entries are JSON objects (and skips non-object node/instance entries and rejects non-object data/service values) before calling member accessors.",
    "evidence": "osv:CVE-2026-87849",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-87849",
      "aliases": [
        "CVE-2026-87849"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/apache/brpc",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "94f1bbd32845a45f0218dfe43e25791252bdcb72"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.18.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.18.0"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.13.0",
            "1.0.0",
            "1.0.0-rc02",
            "1.0.0-rc01",
            "0.9.8-rc01",
            "0.9.7-rc02",
            "0.9.7-rc03",
            "0.9.7",
            "0.9.7-rc01",
            "0.9.6-rc03",
            "0.9.6-rc02",
            "0.9.6-rc01",
            "0.9.6",
            "0.9.5",
            "v0.9.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-87849.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:48.876832409Z",
      "provider": "osv",
      "references": [
        "https://github.com",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/87xxx/CVE-2026-87849.json",
        "https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-87849",
        "https://github.com/apache/brpc/pull/3533"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-125"
        ],
        "cna_assigner": "apache",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/87xxx/CVE-2026-87849.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-87849",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517188,
  "published_at": "2026-10-21T12:18:29.706+00:00"
}