CVE-2026-34459: Sandboxie-Plus sandbox escape via uninitialized memory leak and stack overflow in GetRawInputDeviceInfoSlave

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-05-05 · updated 2026-07-24
Weakness: CWE-121

Description

Sandboxie-Plus is an open source sandbox-based isolation software for Windows. In versions 1.17.2 and earlier, the SbieSvc proxy service's GetRawInputDeviceInfoSlave handler contains two vulnerabilities that can be chained for sandbox escape. First, when a sandboxed process sends an IPC request with cbSize set to 0, up to 32KB of uninitialized stack memory from the service process is returned, leaking return addresses and stack cookies which bypass ASLR and /GS protections. Second, the handler performs a memcpy with an attacker-controlled length without verifying it fits within the 32KB stack buffer, enabling a stack buffer overflow. By chaining the information leak with the overflow, a sandboxed process can execute a ROP chain to achieve SYSTEM privilege escalation, even from a Security Hardened Sandbox. Hardware-enforced shadow stacks (Intel CET) prevent the ROP chain execution but do not mitigate the information leak. This issue has been fixed in version 1.17.3.

Affected products

sandboxie-plus Sandboxie: before 1.17.3 — fixed in 1.17.3

How to fix

Upgrade to a fixed version: sandboxie-plus Sandboxie 1.17.3. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-34459 or the next vulnerability affects your stack