CVE-2026-34459

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.

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CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.02%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-121 CWE-121

Affected Products

Vendor	Product	Versions
sandboxie-plus	sandboxie	< 1.17.3

References

Advisories & Patches

https://github.com/sandboxie-plus/Sandboxie/security/advisories/GHSA-7cpc-5hv7-rfmh https://github.com/sandboxie-plus/Sandboxie/security/advisories/GHSA-7cpc-5hv7-rfmh

Exploits

https://github.com/sandboxie-plus/Sandboxie/security/advisories/GHSA-7cpc-5hv7-rfmh https://github.com/sandboxie-plus/Sandboxie/security/advisories/GHSA-7cpc-5hv7-rfmh

Frequently Asked Questions

What is CVE-2026-34459? +

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. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-34459? +

CVE-2026-34459 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-34459? +

CVE-2026-34459 affects products from sandboxie-plus, specifically: sandboxie. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-34459? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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