{"id":"CVE-2026-21878","aliases":["EUVD-2026-6026","GHSA-p8rx-c26w-545j"],"status":"published","title":"BACnet Stack Improperly Limits Pathnames to a Restricted Directory","description":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0.rc3, a vulnerability has been discovered in BACnet Stack's file writing functionality where there is no validation of user-provided file paths, allowing attackers to write files to arbitrary directories. This affects apps/readfile/main.c and ports/posix/bacfile-posix.c. This vulnerability is fixed in 1.5.0.rc3.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00423,"percentile":0.37044,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-22"],"published":"2026-02-13T18:10:26Z","modified":"2026-10-28T10:59:14Z","products":[{"vendor":"bacnet-stack","product":"bacnet-stack"},{"vendor":"bacnetstack","product":"bacnet_stack"}],"references":[{"url":"https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-p8rx-c26w-545j","tags":["x_refsource_CONFIRM","Exploit","Vendor Advisory","advisory"]},{"url":"https://github.com/bacnet-stack/bacnet-stack/commit/c5dc00a77b4bc2550befa67a930b333e299c18f3","tags":["x_refsource_MISC","Patch","fix"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21878.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21878","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-21878","title":"BACnet Stack Improperly Limits Pathnames to a Restricted Directory","description":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0.rc3, a vulnerability has been discovered in BACnet Stack's file writing functionality where there is no validation of user-provided file paths, allowing attackers to write files to arbitrary directories. This affects apps/readfile/main.c and ports/posix/bacfile-posix.c. This vulnerability is fixed in 1.5.0.rc3.","status":"published","published":"2026-02-13T18:10:26.325Z","modified":"2026-02-13T18:53:59.648Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T13:41:53.237769Z"}],"euvd":[{"id":"EUVD-2026-6026","description":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0.rc3, a vulnerability has been discovered in BACnet Stack's file writing functionality where there is no validation of user-provided file paths, allowing attackers to write files to arbitrary directories. This affects apps/readfile/main.c and ports/posix/bacfile-posix.c. This vulnerability is fixed in 1.5.0.rc3.","status":"published","published":"2026-02-13T18:10:26Z","modified":"2026-02-13T18:53:59Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T19:48:39.919829Z"}],"nvd":[{"id":"CVE-2026-21878","description":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0.rc3, a vulnerability has been discovered in BACnet Stack's file writing functionality where there is no validation of user-provided file paths, allowing attackers to write files to arbitrary directories. This affects apps/readfile/main.c and ports/posix/bacfile-posix.c. This vulnerability is fixed in 1.5.0.rc3.","status":"published","published":"2026-02-13T19:17:28.65Z","modified":"2026-06-17T10:19:04.633Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T14:12:05.908608Z"}],"osv":[{"id":"CVE-2026-21878","title":"BACnet Stack Improperly Limits Pathnames to a Restricted Directory","description":"BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0.rc3, a vulnerability has been discovered in BACnet Stack's file writing functionality where there is no validation of user-provided file paths, allowing attackers to write files to arbitrary directories. This affects apps/readfile/main.c and ports/posix/bacfile-posix.c. This vulnerability is fixed in 1.5.0.rc3.","status":"published","published":"2026-02-13T18:10:26.325Z","modified":"2026-10-28T10:59:14.009405936Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T15:44:58.42038Z"}]}}