Sandboxie-Plus CVE-2026-34464

Attacker must already have code execution inside an active Sandboxie-Plus sandbox on a system running versions 1.17.2 or earlier. The sandboxed process must have access to the SbieSvc service pipe, which is granted by default to all sandboxed processes as part of normal Sandboxie operation. Successful exploitation requires crafting a NAMED_PIPE_OPEN_REQ message with a non-null-terminated server field and controlling the subsequent stack overflow to achieve reliable code execution, complicated by modern Windows exploit mitigations including ASLR, DEP, and stack canaries (contributing to CVSS AC:H rating). This is not a remote attack - the attacker must first convince a user to execute code within a Sandboxie sandbox, which users do intentionally when analyzing untrusted software or documents. Exploitation is limited to Windows systems with Sandboxie-Plus installed and the SbieSvc service running.

CVSS 8.8 (High) with AV:L/AC:H/PR:L reflects the local attack vector requiring low-privileged access within an existing sandbox, but the high attack complexity (AC:H) and present attack requirements (AT:P) suggest exploitation prerequisites are non-trivial. However, the CVSS vector shows VC:H/VI:H/VA:H with scope change indicators SC:H/SI:H/SA:H, indicating complete compromise of confidentiality, integrity, and availability beyond the vulnerable component's security scope - precisely what a sandbox escape enables. The real-world risk is significant because this completely defeats Sandboxie's isolation purpose: malware researchers, enterprises, and users rely on Sandboxie to safely execute untrusted code, and this vulnerability allows that untrusted code to break containment and achieve SYSTEM-level execution on the host. The AC:H rating may reflect exploitation complexity (precise buffer overflow control, ASLR/DEP bypass requirements), but for sophisticated malware authors, sandbox escapes are high-value targets. No CISA KEV listing or public POC exists, suggesting exploitation has not been widespread, but the GitHub Security Advisory publication means full technical details are public knowledge. EPSS data is unavailable for risk quantification. The fix in version 1.17.3 indicates the vendor treated this as a critical security boundary failure requiring immediate patching.

An attacker places malicious code inside a Sandboxie sandbox, such as a downloaded executable or malicious document macro. The malicious code crafts a NAMED_PIPE_OPEN_REQ message with the server[48] field filled with 48 non-zero wide characters and additional controlled data appended beyond the structure boundary. When the sandboxed process sends this request to the SbieSvc service via the restricted service pipe, NamedPipeServer::OpenHandler calls wcscat without validating null termination, causing a stack buffer overflow in the SYSTEM-privileged service. With careful control of overflow data and exploitation techniques to bypass ASLR/DEP, the attacker achieves code execution as SYSTEM, escaping the sandbox and gaining full control of the host system.