Sandboxie-Plus local privilege escalation via TOCTOU race condition in UpdUtil addon installation
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-34596
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 05:16 UTC · Revision 1
Source evidence
Sandboxie-Plus local privilege escalation via TOCTOU race condition in UpdUtil addon installation
core-osv · Original sourcePublished 5 May 2026, 19:34 UTC
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.
osv:CVE-2026-34596
Complete source record
{
"id": "a8ce163be3902ce6376f51afa824aec3e68e7973a3588ba48a9116ba36537f8b",
"url": "https://osv.dev/vulnerability/CVE-2026-34596",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Sandboxie-Plus local privilege escalation via TOCTOU race condition in UpdUtil addon installation",
"summary": "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.",
"evidence": "osv:CVE-2026-34596",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2026-34596",
"aliases": [
"CVE-2026-34596",
"GHSA-xjvp-63f2-v585"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
}
],
"affected": [
{
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{
"repo": "https://github.com/sandboxie-plus/sandboxie",
"type": "GIT",
"events": [
{
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},
{
"fixed": "4f0dbecdcc10063ad1fa7c8f1080419613921f4a"
}
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{
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{
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"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"cpe": "cpe:2.3:a:sandboxie-plus:sandboxie:*:*:*:*:plus:*:*:*",
"range": [
{
"introduced": "0"
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{
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}
],
"source": "CPE_RANGE"
}
]
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}
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"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-34596.json"
}
}
],
"modified": "2026-10-28T02:30:33.344499102Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34596.json",
"https://github.com/sandboxie-plus/Sandboxie/security/advisories/GHSA-xjvp-63f2-v585",
"https://nvd.nist.gov/vuln/detail/CVE-2026-34596"
],
"provider_metadata": {
"cwe_ids": [
"CWE-367"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34596.json"
}
},
"related_cves": [
{
"value": "CVE-2026-34596",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 500463,
"published_at": "2026-05-05T19:34:50.986+00:00"
}