{"id":"CVE-2026-11826","summary":"OpenPLC_v3 Heap-Based Buffer Overflow in Modbus Master getData()","details":"OpenPLC_v3 contains a heap-based buffer overflow in the getData() function in webserver/core/modbus_master.cpp. getData() reads characters between two delimiters into a caller-supplied buffer with no size parameter and no bounds check. In parseConfig() the function is invoked with the 100-byte heap-allocated MB_device.dev_name field. An authenticated attacker with access to the OpenPLC web interface can send a crafted HTTP POST to the /modbus endpoint with an oversized device_name value; the value is persisted to mbconfig.cfg and parsed on load, overflowing dev_name and overwriting adjacent struct fields (protocol at offset 108, dev_address at offset 109, ip_port at offset 210). A 200-byte payload writes 100 bytes past the allocation. The result is heap corruption leading to runtime crash and denial of service of the PLC process control loop, with attacker-controlled overwrite of adjacent configuration fields. The upstream repository was archived on 2026-04-04 and no fix is expected; the vendor has confirmed the issue does not affect OpenPLC Runtime v4.","modified":"2026-10-21T09:41:59.002972947Z","published":"2026-07-18T13:35:35.639Z","database_specific":{"cna_assigner":"VulnCheck","cwe_ids":["CWE-122"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/11xxx/CVE-2026-11826.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/11xxx/CVE-2026-11826.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-11826"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/openplc-v3-heap-based-buffer-overflow-in-modbus-master-getdata"},{"type":"FIX","url":"https://github.com/thiagoralves/OpenPLC_v3/commit/b4702061dc14d1024856f71b4543298d77007b88"},{"type":"PACKAGE","url":"https://github.com/thiagoralves/OpenPLC_v3"},{"type":"ARTICLE","url":"https://gist.github.com/Shukhrat-03/5cf1825b72e485ef98a32958dfbc611a#security-vulnerability-report"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/thiagoralves/openplc_v3","events":[{"introduced":"0"},{"fixed":"b4702061dc14d1024856f71b4543298d77007b88"}],"database_specific":{"extracted_events":[{"range":[{"introduced":"0"},{"last_affected":"b470206"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"},{"range":[{"fixed":"b4702061dc14d1024856f71b4543298d77007b88"}],"source":"REFERENCES_COMMIT"}]}}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-11826.json","vanir_signatures":[{"id":"CVE-2026-11826-eecd8351","signature_type":"Line","signature_version":"v1","source":"https://github.com/thiagoralves/openplc_v3/commit/b4702061dc14d1024856f71b4543298d77007b88","target":{"file":"webserver/core/lib/iec_std_functions.h"},"deprecated":false,"digest":{"line_hashes":["326100465535811451797659690864422037342","247389525188167108479582712171041193944","149524828771016141953941075005619685773","75162787984455876771617289835268377032","286723267192876252689923870444567925926","132645819700948482782421974211161025787","32354695468714309932117234454075294451","271059337889115762102703437314768354834","2433743029965955582598453748383349321","330881237858063270492938961009165433822","250748072820325620700844646605942732022","318144474659556132839530946772984104242","50281942822181363972853591006668747656","8075137283112446911143253807893132260","50176584540348879614342907472233298027"],"threshold":0.9}}],"vanir_signatures_modified":"2026-10-21T09:41:59Z"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"}]}