# CVE-2026-34464: Sandboxie-Plus NamedPipeServer OpenHandler stack overflow via unterminated server field

> A stack overflow in Sandboxie-Plus allows sandboxed callers to execute code as SYSTEM, enabling sandbox escape and privilege escalation.

- **Severity:** High 8.8 (`CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 May 2026
- **Updated:** 7 May 2026
- **Also known as:** GHSA-cf8x-f33g-vwfg

## What is CVE-2026-34464?

CVE-2026-34464 is a high-severity memory corruption vulnerability in sandboxie-plus Sandboxie, published on 5 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Sandboxie-Plus is an open source sandbox-based isolation software for Windows. In versions 1.17.2 and earlier, NamedPipeServer::OpenHandler copies the server field from NAMED_PIPE_OPEN_REQ into a fixed WCHAR pipename[160] stack buffer using wcscat without verifying null termination. The handler only enforces a minimum packet size, and since the service pipe accepts variable-length messages, a sandboxed caller can fill the server[48] field with non-zero data and append additional controlled wide characters after the structure. wcscat then reads past the fixed field and overflows the stack buffer in the SYSTEM service. This message is restricted to sandboxed callers, making it a sandbox escape vector. This can lead to a crash of the SbieSvc service or potential code execution as SYSTEM. This issue has been fixed in version 1.17.3.

Weakness: CWE-170 (Improper Null Termination), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-34464?

It affects 1 product.


Products: Sandboxie-Plus Sandboxie.

## How do I fix CVE-2026-34464?

No fix has been published for CVE-2026-34464 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34464 being exploited?

There is no known exploitation of CVE-2026-34464 in the wild and no public exploit code.

## Other vulnerabilities in sandboxie-plus Sandboxie

- [CVE-2018-18748](https://insights.sbomify.com/CVE-2018-18748/): Security feature bypass in n/a (critical 10.0)
- [CVE-2025-64721](https://insights.sbomify.com/CVE-2025-64721/): Sandboxie's Integer Overflow in SbieIniServer::RC4Crypt allows sandbox escape and SYSTEM compromise (critical 9.9)
- [CVE-2026-34458](https://insights.sbomify.com/CVE-2026-34458/): Sandboxie-Plus privilege escalation via INI CRLF injection bypassing EditAdminOnly (critical 9.3)
- [CVE-2024-49360](https://insights.sbomify.com/CVE-2024-49360/): Path traversal in Sandboxie (critical 9.2)
- [CVE-2026-34459](https://insights.sbomify.com/CVE-2026-34459/): Sandboxie-Plus sandbox escape via uninitialized memory leak and stack overflow in GetRawInputDeviceInfoSlave (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34464 and fix it if it is affected.

What it is: CVE-2026-34464 is a high-severity memory corruption vulnerability in sandboxie-plus Sandboxie, published on 5 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-34464 in the wild and no public exploit code.

Affected product: sandboxie-plus Sandboxie. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-34464/ (Markdown: https://insights.sbomify.com/CVE-2026-34464/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34464
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34464
- OSV: https://osv.dev/vulnerability/CVE-2026-34464

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-34464/
Summaries are generated and may contain mistakes; the official description above is the record.