{"id":"CVE-2021-21787","aliases":["EUVD-2021-8959","GHSA-2894-2ggj-v24h"],"status":"published","title":"A privilege escalation vulnerability exists in the way IOBit Advanced SystemCare Ultimate 14.2.0...","description":"A privilege escalation vulnerability exists in the way IOBit Advanced SystemCare Ultimate 14.2.0.220 driver handles Privileged I/O write requests. During IOCTL 0x9c40a0d8, the first dword passed in the input buffer is the device port to write to and the byte at offset 4 is the value to write via the OUT instruction. The OUT instruction can write one byte to the given I/O device port, potentially leading to escalated privileges of unprivileged users.","severity":{"version":"3.0","score":8.8,"vector":"CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00338,"percentile":0.27481,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-782"],"published":"2021-07-07T16:39:44Z","modified":"2026-06-17T03:36:07Z","products":[{"vendor":"iobit","product":"advanced_systemcare_ultimate"}],"references":[{"url":"https://talosintelligence.com/vulnerability_reports/TALOS-2021-1254","tags":["x_refsource_MISC","x_transferred","Exploit","Third Party Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21787"},{"url":"https://github.com/advisories/GHSA-2894-2ggj-v24h"}],"sources":{"cve":[{"id":"CVE-2021-21787","description":"A privilege escalation vulnerability exists in the way IOBit Advanced SystemCare Ultimate 14.2.0.220 driver handles Privileged I/O write requests. During IOCTL 0x9c40a0d8, the first dword passed in the input buffer is the device port to write to and the byte at offset 4 is the value to write via the OUT instruction. The OUT instruction can write one byte to the given I/O device port, potentially leading to escalated privileges of unprivileged users.","status":"published","published":"2021-07-07T16:39:44Z","modified":"2024-08-03T18:23:29.434Z","cvss":[{"version":"3.0","score":8.8,"vector":"CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-782"],"updated_at":"2026-11-02T14:33:00.137099Z"}],"euvd":[{"id":"EUVD-2021-8959","description":"A privilege escalation vulnerability exists in the way IOBit Advanced SystemCare Ultimate 14.2.0.220 driver handles Privileged I/O write requests. During IOCTL 0x9c40a0d8, the first dword passed in the input buffer is the device port to write to and the byte at offset 4 is the value to write via the OUT instruction. The OUT instruction can write one byte to the given I/O device port, potentially leading to escalated privileges of unprivileged users.","status":"published","published":"2021-07-07T16:39:44Z","modified":"2024-08-03T18:23:29Z","cvss":[{"version":"3.0","score":8.8,"vector":"CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-03T03:25:05.131984Z"}],"ghsa":[{"id":"GHSA-2894-2ggj-v24h","title":"A privilege escalation vulnerability exists in the way IOBit Advanced SystemCare Ultimate 14.2.0...","description":"A privilege escalation vulnerability exists in the way IOBit Advanced SystemCare Ultimate 14.2.0.220 driver handles Privileged I/O write requests. During IOCTL 0x9c40a0d8, the first dword passed in the input buffer is the device port to write to and the byte at offset 4 is the value to write via the OUT instruction. The OUT instruction can write one byte to the given I/O device port, potentially leading to escalated privileges of unprivileged users.","status":"published","published":"2022-05-24T19:06:58Z","modified":"2023-01-30T05:00:37Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T14:46:14.46933Z"}],"nvd":[{"id":"CVE-2021-21787","description":"A privilege escalation vulnerability exists in the way IOBit Advanced SystemCare Ultimate 14.2.0.220 driver handles Privileged I/O write requests. During IOCTL 0x9c40a0d8, the first dword passed in the input buffer is the device port to write to and the byte at offset 4 is the value to write via the OUT instruction. The OUT instruction can write one byte to the given I/O device port, potentially leading to escalated privileges of unprivileged users.","status":"published","published":"2021-07-07T17:15:07.957Z","modified":"2026-06-17T03:36:07Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high","assessor":"primary"},{"version":"3.0","score":8.8,"vector":"CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","level":"high","assessor":"secondary"},{"version":"2.0","score":4.6,"vector":"AV:L/AC:L/Au:N/C:P/I:P/A:P","level":"medium","assessor":"primary"}],"cwes":["CWE-782"],"updated_at":"2026-11-02T14:06:55.259633Z"}]}}