What is the CVSS score of CVE-2026-45313?

CVE-2026-45313 has a CVSS 3.1 base score of 7.7 (High). CVSS vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.1%.

Which versions of Sandboxie-Plus are affected by CVE-2026-45313?

Sandboxie-Plus before version 1.17.6 contains a sandbox escape vulnerability allowing SYSTEM-level code execution, completely defeating the product's core containment function.

How to fix or mitigate CVE-2026-45313?

Within 24 hours, audit all systems running Sandboxie-Plus versions prior to 1.17.6 and stop using the product for containment of untrusted code; document what applications or workloads were previously sandboxed. Within 7 days, migrate security-critical application isolation to alternative solutions such as Windows Sandbox, Hyper-V isolation, or third-party sandbox platforms; if immediate migration is not feasible, implement strict network segmentation to limit lateral movement from potentially compromised hosts. Within 30 days, establish contact with Sandboxie project maintainers to confirm patch timeline, prepare a staged deployment procedure for version 1.17.6 or later once released, and conduct a security audit of all systems that ran Sandboxie-Plus during the vulnerable window to detect potential exploitation.

Sandboxie-Plus CVE-2026-45313

HIGH

Improper Access Control (CWE-284)

2026-07-15 GitHub_M

Authentication Bypass Microsoft RCE Sandboxie

7.7

CVSS 3.1 · Vendor: GitHub_M

Severity by source

Vendor (GitHub_M) PRIMARY

7.7 HIGH

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

vuln.today AI

7.8 HIGH

Attacker must already run code inside a sandbox (AV:L, PR:L); reaching the hook-notify path needs specific timing (AC:H); escape to SYSTEM host crosses trust boundary (S:C) with full C/I/A impact.

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

4.0 AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

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

Attack Vector

Local

Attack Complexity

High

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Source Code Evidence Fetched

Jul 15, 2026 - 22:06 vuln.today

Analysis Generated

Jul 15, 2026 - 22:06 vuln.today

CVE Published

Jul 15, 2026 - 21:21 cve.org

HIGH 7.7

DescriptionCVE.org

Sandboxie-Plus is an open source sandbox-based isolation software for Windows. Prior to 1.17.6, GuiServer::WndHookRegisterSlave in Sandboxie/core/svc/GuiServer.cpp stores attacker-supplied hthread and hproc fields from a GUI_WND_HOOK_REGISTER request without validating that the thread belongs to the sandboxed process or that the function pointer is in the caller address space, and GuiServer::WndHookNotifySlave then calls OpenThread(THREAD_SET_CONTEXT, FALSE, whk->hthread) and QueueUserAPC((PAPCFUNC)whk->hproc, hThread, (ULONG_PTR)req->threadid) as SYSTEM, allowing a sandboxed process to execute arbitrary code in an unsandboxed host process. This issue is fixed in version 1.17.6.

AnalysisAI

Sandbox escape with SYSTEM-level code execution in Sandboxie-Plus before 1.17.6 allows a process confined inside a sandbox to run arbitrary code in an unsandboxed host process. The privileged GuiServer service trusts attacker-supplied thread and function-pointer values from a GUI window-hook registration request and dispatches them via QueueUserAPC while running as SYSTEM, defeating the core isolation guarantee of the product. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access

Gain code execution inside sandboxed process

Delivery

Craft GUI_WND_HOOK_REGISTER with malicious hthread/hproc

Exploit

Send request to SYSTEM GuiServer

Execution

Trigger WndHookNotifySlave QueueUserAPC path

Persist

Execute attacker pointer as SYSTEM in host

Impact

Escape sandbox, full system compromise

Access

Gain code execution inside sandboxed process

Delivery

Craft GUI_WND_HOOK_REGISTER with malicious hthread/hproc

Exploit

Send request to SYSTEM GuiServer

Execution

Trigger WndHookNotifySlave QueueUserAPC path

Persist

Execute attacker pointer as SYSTEM in host

Impact

Escape sandbox, full system compromise

Vulnerability AssessmentAI

Exploitation	Exploitation requires the attacker to first be running code inside a Sandboxie-Plus sandbox (a sandboxed process) so they can issue a GUI_WND_HOOK_REGISTER request to the local SYSTEM GuiServer - this is a local sandbox-escape, not a remote attack. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment	The supplied CVSS 3.1 base score is 7.7 (High) with vector AV:L/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H - local vector, high attack complexity, scope change, and full confidentiality/integrity/availability impact, which correctly captures a boundary-crossing escape. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	An attacker who has already achieved code execution inside a Sandboxie box - for example by luring a user to open malicious content in a sandboxed browser - sends a crafted GUI_WND_HOOK_REGISTER request to the SYSTEM GuiServer with an hthread handle and an hproc function pointer under their control. When the hook fires, GuiServer executes the attacker's pointer via QueueUserAPC as SYSTEM in a host process, breaking out of the sandbox and elevating to full system compromise. …
Remediation	Vendor-released patch: 1.17.6 (classic 5.72.6) - upgrade all installations to this version or later, per advisory GHSA-rmv3-fhg3-75xh and the release at https://github.com/sandboxie-plus/Sandboxie/releases/tag/v1.17.6, which adds the missing validation of the hthread/hproc fields in GuiServer's window-hook handling. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, audit all systems running Sandboxie-Plus versions prior to 1.17.6 and stop using the product for containment of untrusted code; document what applications or workloads were previously sandboxed. …

Threat intelligence, references, and detailed analysis are available after sign-in.