{"id":"CVE-2026-26264","aliases":["EUVD-2026-6027","GHSA-phjh-v45p-gmjj"],"status":"published","title":"BACnet Stack WriteProperty decoding length underflow leads to OOB read and crash","description":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0rc4 and 1.4.3rc2, a malformed WriteProperty request can trigger a length underflow in the BACnet stack, leading to an out‑of‑bounds read and a crash (DoS). The issue is in wp.c within wp_decode_service_request. When decoding the optional priority context tag, the code passes apdu_len - apdu_size to bacnet_unsigned_context_decode without validating that apdu_size \u003c= apdu_len. If a truncated APDU reaches this path, apdu_len - apdu_size underflows, resulting in a large size being used for decoding and an out‑of‑bounds read. This vulnerability is fixed in 1.5.0rc4 and 1.4.3rc2.","severity":{"version":"4.0","score":7.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:P","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00437,"percentile":0.38279,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-125"],"published":"2026-02-13T18:14:30Z","modified":"2026-10-28T10:51:19Z","products":[{"vendor":"bacnet-stack","product":"bacnet-stack"},{"vendor":"bacnetstack","product":"bacnet_stack"}],"references":[{"url":"https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-phjh-v45p-gmjj","tags":["x_refsource_CONFIRM","Exploit","Vendor Advisory","advisory"]},{"url":"https://github.com/bacnet-stack/bacnet-stack/commit/4cc8067c86f26e2b08b2c8f4d27f8e07de4d4708","tags":["x_refsource_MISC","Patch","fix"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26264.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-26264","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-26264","title":"BACnet Stack WriteProperty decoding length underflow leads to OOB read and crash","description":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0rc4 and 1.4.3rc2, a malformed WriteProperty request can trigger a length underflow in the BACnet stack, leading to an out‑of‑bounds read and a crash (DoS). The issue is in wp.c within wp_decode_service_request. When decoding the optional priority context tag, the code passes apdu_len - apdu_size to bacnet_unsigned_context_decode without validating that apdu_size \u003c= apdu_len. If a truncated APDU reaches this path, apdu_len - apdu_size underflows, resulting in a large size being used for decoding and an out‑of‑bounds read. This vulnerability is fixed in 1.5.0rc4 and 1.4.3rc2.","status":"published","published":"2026-02-13T18:14:30.232Z","modified":"2026-02-13T18:50:30.367Z","cvss":[{"version":"4.0","score":7.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:P","level":"high","assessor":"cna"}],"cwes":["CWE-125"],"updated_at":"2026-11-02T13:38:20.971157Z"}],"euvd":[{"id":"EUVD-2026-6027","description":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0rc4 and 1.4.3rc2, a malformed WriteProperty request can trigger a length underflow in the BACnet stack, leading to an out‑of‑bounds read and a crash (DoS). The issue is in wp.c within wp_decode_service_request. When decoding the optional priority context tag, the code passes apdu_len - apdu_size to bacnet_unsigned_context_decode without validating that apdu_size \u003c= apdu_len. If a truncated APDU reaches this path, apdu_len - apdu_size underflows, resulting in a large size being used for decoding and an out‑of‑bounds read. This vulnerability is fixed in 1.5.0rc4 and 1.4.3rc2.","status":"published","published":"2026-02-13T18:14:30Z","modified":"2026-02-13T18:50:30Z","cvss":[{"version":"4.0","score":7.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:P","level":"high"}],"updated_at":"2026-11-02T19:48:39.919829Z"}],"nvd":[{"id":"CVE-2026-26264","description":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0rc4 and 1.4.3rc2, a malformed WriteProperty request can trigger a length underflow in the BACnet stack, leading to an out‑of‑bounds read and a crash (DoS). The issue is in wp.c within wp_decode_service_request. When decoding the optional priority context tag, the code passes apdu_len - apdu_size to bacnet_unsigned_context_decode without validating that apdu_size \u003c= apdu_len. If a truncated APDU reaches this path, apdu_len - apdu_size underflows, resulting in a large size being used for decoding and an out‑of‑bounds read. This vulnerability is fixed in 1.5.0rc4 and 1.4.3rc2.","status":"published","published":"2026-02-13T19:17:31.143Z","modified":"2026-06-17T10:26:00.427Z","cvss":[{"version":"4.0","score":7.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","level":"high","assessor":"primary"}],"cwes":["CWE-125"],"updated_at":"2026-11-02T14:12:05.908608Z"}],"osv":[{"id":"CVE-2026-26264","title":"BACnet Stack WriteProperty decoding length underflow leads to OOB read and crash","description":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0rc4 and 1.4.3rc2, a malformed WriteProperty request can trigger a length underflow in the BACnet stack, leading to an out‑of‑bounds read and a crash (DoS). The issue is in wp.c within wp_decode_service_request. When decoding the optional priority context tag, the code passes apdu_len - apdu_size to bacnet_unsigned_context_decode without validating that apdu_size \u003c= apdu_len. If a truncated APDU reaches this path, apdu_len - apdu_size underflows, resulting in a large size being used for decoding and an out‑of‑bounds read. This vulnerability is fixed in 1.5.0rc4 and 1.4.3rc2.","status":"published","published":"2026-02-13T18:14:30.232Z","modified":"2026-10-28T10:51:19.899677368Z","cvss":[{"version":"4.0","score":7.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:P","level":"high"}],"cwes":["CWE-125"],"updated_at":"2026-11-02T15:44:59.80315Z"}]}}