Which versions of Sandboxie-Plus are affected by CVE-2026-34458?

Sandboxie-Plus versions 1.17.2 and earlier contain a critical privilege escalation vulnerability that allows any local user to inject malicious configuration directives and gain SYSTEM-level access,…. A patch is available.

How to fix or mitigate CVE-2026-34458?

Within 24 hours: Identify all systems running Sandboxie-Plus 1.17.2 or earlier via endpoint inventory. Within 7 days: Upgrade all affected instances to Sandboxie-Plus version 1.17.3 or later; restrict local user access to machines running vulnerable versions where immediate patching is not feasible. Within 30 days: Verify 100% completion of upgrades and audit logs for unauthorized sandbox modifications or privilege escalation attempts.

Sandboxie-Plus CVE-2026-34458

Q: What is the CVSS score of CVE-2026-34458?

CVE-2026-34458 has a CVSS 4.0 base score of 9.3 (Critical). CVSS vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.0%.

EUVD-2026-27456 CRITICAL

Improper Neutralization of CRLF Sequences ('CRLF Injection') (CWE-93)

2026-05-05 GitHub_M

Privilege Escalation Microsoft

9.3

CVSS 4.0 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

9.3 CRITICAL

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Patch available

May 05, 2026 - 21:02 EUVD

Source Code Evidence Fetched

May 05, 2026 - 20:30 vuln.today

Analysis Generated

May 05, 2026 - 20:30 vuln.today

CVSS changed

May 05, 2026 - 20:22 NVD

9.3 (CRITICAL)

DescriptionGitHub Advisory

Sandboxie-Plus is an open source sandbox-based isolation software for Windows. In versions 1.17.2 and earlier, an INI injection vulnerability allows any standard local user to bypass configuration restrictions (EditAdminOnly and ConfigPassword) and inject arbitrary directives into the global Sandboxie.ini configuration file. The background service skips authorization checks for IPC messages targeting sections beginning with UserSettings_, but does not sanitize CRLF characters in either the value parameter (via MSGID_SBIE_INI_ADD_SETTING) or the setting name parameter (via MSGID_SBIE_INI_SET_SETTING). An attacker can inject a new sandbox section header with unrestricted permissions, enabling sandbox escape and SYSTEM privilege escalation. This issue has been fixed in version 1.17.3.

AnalysisAI

INI injection in Sandboxie-Plus versions 1.17.2 and earlier enables any local low-privilege user to bypass EditAdminOnly and ConfigPassword protections, inject malicious directives into the global Sandboxie.ini file, create unrestricted sandbox sections, and escalate to SYSTEM privileges. The background service fails to authorize IPC messages for UserSettings_* sections and does not sanitize CRLF characters in MSGID_SBIE_INI_ADD_SETTING and MSGID_SBIE_INI_SET_SETTING parameters, allowing section header injection. Fixed in version 1.17.3 released by the vendor. No CISA KEV listing or public exploit identified at time of analysis, but technical details in GitHub advisory provide sufficient information for exploit development.

Technical ContextAI

Sandboxie-Plus is a Windows sandbox isolation application that uses a background service (running as SYSTEM) to enforce sandbox policies defined in Sandboxie.ini. The vulnerability exists in the service's IPC message handling for configuration updates. The root cause is CWE-93 (Improper Neutralization of CRLF Sequences), where the service accepts MSGID_SBIE_INI_ADD_SETTING and MSGID_SBIE_INI_SET_SETTING messages targeting UserSettings_* sections without proper authorization, and fails to sanitize carriage return/line feed characters in value or setting name parameters. An attacker can inject literal CRLF sequences to break out of the intended UserSettings_ section and write arbitrary configuration sections, including new sandbox definitions with elevated permissions (e.g., DropAdminRights=N, OpenWinClass=*). This transforms a restricted user-settings capability into full configuration file write access.

RemediationAI

Upgrade to Sandboxie-Plus version 1.17.3 or later, released by the vendor to resolve CVE-2026-34458 and additional security issues including CVE-2026-32603, ProcessServer name validation weaknesses, and NamedPipeServer parameter validation flaws. Download from official GitHub release page: https://github.com/sandboxie-plus/Sandboxie/releases/tag/v1.17.3. If immediate patching is not feasible, restrict local user access to systems running Sandboxie-Plus and audit user accounts with local logon rights-compensating controls are limited since the vulnerability requires only standard user credentials. Note that version 1.17.3 also introduces salted SHA-256 password hashing for EditPassword, but existing passwords remain in weaker format until manually changed; administrators should rotate ConfigPassword after upgrading to benefit from improved entropy.