{"id":"CVE-2021-33626","title":"A vulnerability exists in SMM (System Management Mode) branch that registers a SWSMI handler that does not sufficiently check or validate the allocated buffer pointer(QWORD values for CommBuffer)","summary":"A vulnerability exists in SMM (System Management Mode) branch that registers a SWSMI handler that does not sufficiently check or validate the allocated buffer pointer(QWORD values for CommBuffer). This can be used by an attacker to corru…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-829"],"vendor":"insyde","product":"insydeh2o","affected":["insydeh2o >= 5.3, < 5.34.44","insydeh2o >= 5.2, < 5.25.44","insydeh2o >= 5.1, < 5.16.25","insydeh2o >= 5.4, < 5.42.44","insydeh2o >= 5.3, < 5.35.25","insydeh2o >= 5.2, < 5.26.25","insydeh2o >= 5.4, < 5.43.25","ruggedcom_apr1808_firmware","simatic_field_pg_m5_firmware","simatic_field_pg_m6_firmware","simatic_ipc127e_firmware","simatic_ipc227g_firmware","simatic_ipc277g_firmware","simatic_ipc327g_firmware","simatic_ipc377g_firmware","simatic_ipc427e_firmware","simatic_ipc477e_firmware","simatic_ipc477e_pro_firmware","simatic_ipc627e_firmware","simatic_ipc647e_firmware","simatic_ipc677e_firmware","simatic_ipc847e_firmware","simatic_itp1000_firmware"],"patched":["insydeh2o 5.43.25"],"published":"2021-10-01","updated":"2026-08-11","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-33626","references":[{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf","label":"cve@mitre.org"},{"url":"https://security.netapp.com/advisory/ntap-20220216-0006/","label":"cve@mitre.org"},{"url":"https://www.insyde.com/security-pledge","label":"cve@mitre.org"},{"url":"https://www.insyde.com/security-pledge/SA-2021001","label":"cve@mitre.org"},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20220216-0006/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.insyde.com/security-pledge","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.insyde.com/security-pledge/SA-2021001","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.kb.cert.org/vuls/id/796611","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-306654.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd"],"epss":0.00308,"epssPercentile":0.23747,"ingestedAt":"2026-08-11T16:47:01.478Z","slug":"CVE-2021-33626","body":"## Overview\n\nA vulnerability exists in SMM (System Management Mode) branch that registers a SWSMI handler that does not sufficiently check or validate the allocated buffer pointer(QWORD values for CommBuffer). This can be used by an attacker to corrupt data in SMRAM memory and even lead to arbitrary code execution.\n\n## Affected\n\n- `insydeh2o >= 5.3, < 5.34.44`\n- `insydeh2o >= 5.2, < 5.25.44`\n- `insydeh2o >= 5.1, < 5.16.25`\n- `insydeh2o >= 5.4, < 5.42.44`\n- `insydeh2o >= 5.3, < 5.35.25`\n- `insydeh2o >= 5.2, < 5.26.25`\n- `insydeh2o >= 5.4, < 5.43.25`\n- `ruggedcom_apr1808_firmware`\n- `simatic_field_pg_m5_firmware`\n- `simatic_field_pg_m6_firmware`\n- `simatic_ipc127e_firmware`\n- `simatic_ipc227g_firmware`\n- `simatic_ipc277g_firmware`\n- `simatic_ipc327g_firmware`\n- `simatic_ipc377g_firmware`\n- `simatic_ipc427e_firmware`\n- `simatic_ipc477e_firmware`\n- `simatic_ipc477e_pro_firmware`\n- `simatic_ipc627e_firmware`\n- `simatic_ipc647e_firmware`\n- `simatic_ipc677e_firmware`\n- `simatic_ipc847e_firmware`\n- `simatic_itp1000_firmware`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `insydeh2o 5.43.25`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}