BACnet Stack: Off-by-One Out-of-Bounds Read in ReadPropertyMultiple Object ID Decoder

{
  "id": "74f4a3fc3eb138b54fdfb5d49348d576dbc02fb5e94e28bce3c8dad28b30ae7b",
  "url": "https://osv.dev/vulnerability/CVE-2026-41502",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "BACnet Stack: Off-by-One Out-of-Bounds Read in ReadPropertyMultiple Object ID Decoder",
    "summary": "BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.4.3, an off-by-one out-of-bounds read vulnerability in bacnet-stack's ReadPropertyMultiple service decoder allows unauthenticated remote attackers to read one byte past an allocated buffer boundary by sending a crafted RPM request with a truncated object identifier. The vulnerability is in rpm_decode_object_id(), which checks apdu_len < 5 but then accesses all 6 byte positions (indices 0-5) — consuming 1 byte for the context tag, 4 bytes for the object ID, then reading apdu[5] for the opening tag check. A 5-byte input passes the length check but causes a 1-byte OOB read, leading to crashes on embedded BACnet devices. The vulnerability exists in src/bacnet/rpm.c and affects any deployment that enables the ReadPropertyMultiple confirmed service handler (enabled by default in the reference server). This vulnerability is fixed in 1.4.3.",
    "evidence": "osv:CVE-2026-41502",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-41502",
      "aliases": [
        "CVE-2026-41502",
        "GHSA-7545-3fpx-4xw3"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/bacnet-stack/bacnet-stack",
              "type": "GIT",
              "events": [
                {
                  "introduced": "f332225b196aa66503faae64f92bef113fe89ab2"
                },
                {
                  "fixed": "6d2d251ca4f4d932664add702b236279863d630a"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "1.4.0"
                      },
                      {
                        "fixed": "1.4.3"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:bacnetstack:bacnet_stack:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "1.4.0"
                      },
                      {
                        "fixed": "1.4.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "bacnet-stack-1.4.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-41502.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.797916031Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41502.json",
        "https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-7545-3fpx-4xw3",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-41502"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-125",
          "CWE-193"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41502.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-41502",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490081,
  "published_at": "2026-04-24T19:40:43.059+00:00"
}