{"id":"CVE-2026-49990","summary":"BACnet Stack: AtomicReadFile/AtomicWriteFile stream fileStartPosition validation flaw causes out-of-bounds read/write in RAM file backends","details":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. From versions 1.4.2 to before 1.4.5, and 1.5.0 to before 1.5.1, a signed fileStartPosition taken from AtomicReadFile and AtomicWriteFile stream-access requests is not validated tightly enough before it reaches the RAM file backends. Practical impact includes: reliable denial of service via process crash, out-of-bounds read that may expose adjacent memory contents, or out-of-bounds write that may corrupt heap memory and destabilize the process. This issue has been patched in versions 1.4.5 and 1.5.1.","aliases":["GHSA-8759-hx7g-94qx"],"modified":"2026-11-14T10:30:55.963059478Z","published":"2026-11-13T15:54:22.681Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49990.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-125","CWE-787"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49990.json"},{"type":"FIX","url":"https://github.com/bacnet-stack/bacnet-stack/pull/1362"},{"type":"ADVISORY","url":"https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-8759-hx7g-94qx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49990"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/bacnet-stack/bacnet-stack","events":[{"introduced":"0682428c867c50895844d914e0f70be5c67ec917"},{"fixed":"289b90d8d109b00594667a82007255bb71b36a6b"},{"introduced":"61a7a53bea5b5bc4724646abbce601fd26c364b6"},{"fixed":"3a74c74a8139526e34da32c6cc41ed7c71aaded5"}],"database_specific":{"extracted_events":[{"source":"AFFECTED_FIELD","strategy":"StringRangeExpression","range":[{"introduced":"1.4.2"},{"fixed":"1.4.5"}]},{"strategy":"StringRangeExpression","range":[{"introduced":"1.5.0"},{"fixed":"1.5.1"}],"source":"AFFECTED_FIELD"}]}}],"versions":["bacnet-stack-1.5.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-49990.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H"}]}