CVE-2026-34596

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.

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CVSS v3.1 Score

7.0

HIGH

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/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-367 CWE-367

Affected Products

Vendor	Product	Versions
sandboxie-plus	sandboxie	< 1.17.3

References

Advisories & Patches

https://github.com/sandboxie-plus/Sandboxie/security/advisories/GHSA-xjvp-63f2-v585 https://github.com/sandboxie-plus/Sandboxie/security/advisories/GHSA-xjvp-63f2-v585

Exploits

https://github.com/sandboxie-plus/Sandboxie/security/advisories/GHSA-xjvp-63f2-v585 https://github.com/sandboxie-plus/Sandboxie/security/advisories/GHSA-xjvp-63f2-v585

Frequently Asked Questions

What is CVE-2026-34596? +

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. It has a CVSS v3.1 base score of 7.0 (HIGH).

How severe is CVE-2026-34596? +

CVE-2026-34596 has a CVSS v3.1 score of 7.0 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-2026-34596? +

CVE-2026-34596 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-2026-34596? +

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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