Sandboxie‑Plus 1.18.5 and earlier allowed a sandboxed process to send certain IPC messages (MSGID_FILE_SET_ATTRIBUTES and MSGID_FILE_SET_SHORT_NAME) to the SbieSvc system service. These messages instructed SbieSvc to open and modify files outside the sandbox. By changing file attributes, timestamps, write‑access or 8‑3 short names a sandboxed process could alter system files or, through a short‑name redirect, enable privileged code execution if a privileged system service later resolved the attacker‑controlled short‑name path. The flaw therefore permits the modification of arbitrary files on the host, potentially compromising configuration files, drivers, or executables used by privileged users.

Tool affected is Sandboxie‑Plus, the open‑source sandbox isolation product authored by the Sandboxie project. All releases before 1.18.6—including 1.18.5 and earlier—are vulnerable. The vulnerability is fixed in version 1.18.6 and later.

The flaw carries a CVSS score of 6.9, indicating moderate severity. No EPSS value is available, and the vulnerability is not listed in CISA’s KEV catalogue. A required attacker already needs to run code inside a sandbox to trigger the exploit; however, any code executing within a sandbox can send the privileged IPC messages, so local privilege escalation can be achieved without external network access. Because the exploit modifies files at system scope, compromise can lead to denial of service, persistence, or further privilege escalation. Administrators should therefore treat it as a serious local vulnerability until patched.