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 0x9c40a0dc, the first dword passed in the input buffer is the device port to write to and the word 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. A local attacker can send a malicious IRP to trigger this vulnerability.
Conclusion & alert: CVE-2021-21788 is rated Exploit Available (58.7/100): CVSS High severity, with low exploitation likelihood (EPSS 0.32%).Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB).Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
Public exploit references (Exploit-DB) for CVE-2021-21788
Exploit prediction scoring system (EPSS) score for CVE-2021-21788
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).