CVE-2026-34596 Sandboxie-Plus local privilege escalation via TOCTOU race condition in UpdUtil addon installation
An attacker can exploit a race condition during addon installation to execute arbitrary code with SYSTEM privileges on Windows.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-34596?
CVE-2026-34596 is a medium-severity vulnerability in sandboxie-plus Sandboxie, published on 5 May 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Sandboxie-Plus is an open source sandbox-based isolation software for Windows. In versions 1.17.2 and earlier, a Time-of-Check-to-Time-of-Use (TOCTOU) race condition exists during addon installation. When a user installs an addon through the SandMan interface, UpdUtil.exe is spawned as SYSTEM by SbieSvc but stages files in the user-writable %TEMP%\sandboxie-updater directory. After UpdUtil verifies file hashes against the signed addon manifest, install.bat extracts files.cab and executes config.exe from its contents. Between hash verification and extraction, an unprivileged user can replace files.cab with a crafted cabinet containing a malicious executable, which is then run as SYSTEM. No UAC prompt is required.
This issue has been fixed in version 1.17.3.
Weakness: CWE-367
Which versions are affected by CVE-2026-34596?
It affects 1 product.
Products include Sandboxie-Plus Sandboxie.
How do I fix CVE-2026-34596?
No fix has been published for CVE-2026-34596 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-34596 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34596 exists.
Other vulnerabilities in sandboxie-plus Sandboxie
- CVE-2018-18748 Security feature bypass in n/a
- CVE-2025-64721 Sandboxie's Integer Overflow in SbieIniServer::RC4Crypt allows sandbox escape and SYSTEM compromise
- CVE-2026-34458 Sandboxie-Plus privilege escalation via INI CRLF injection bypassing EditAdminOnly
- CVE-2024-49360 Path traversal in Sandboxie
- CVE-2026-34459 Sandboxie-Plus sandbox escape via uninitialized memory leak and stack overflow in GetRawInputDeviceInfoSlave
Sources
Also known as GHSA-xjvp-63f2-v585.