CVE-2025-21138: Adobe Substance 3D Designer RCE Flaw

CVE-2025-21138 Overview

CVE-2025-21138 is an out-of-bounds write vulnerability [CWE-787] in Adobe Substance 3D Designer versions 14.0 and earlier. Successful exploitation allows arbitrary code execution in the context of the current user. The flaw requires local access and user interaction: a victim must open a malicious file crafted by an attacker. Adobe published the corresponding security bulletin APSB25-06 on January 14, 2025.

Critical Impact
A crafted Substance 3D Designer project or asset file can trigger memory corruption and execute attacker-controlled code with the privileges of the logged-in user.

Affected Products

Adobe Substance 3D Designer 14.0
Adobe Substance 3D Designer earlier than 14.0
Windows and macOS installations of the affected versions

Discovery Timeline

2025-01-14 - Adobe releases security bulletin APSB25-06
2025-01-14 - CVE-2025-21138 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-21138

Vulnerability Analysis

CVE-2025-21138 is classified as an out-of-bounds write, categorized under [CWE-787]. The condition arises when Substance 3D Designer parses a specifically crafted input file and writes data beyond the bounds of an allocated memory region. Writing outside the intended buffer corrupts adjacent memory structures, which an attacker can leverage to redirect execution flow. Because Substance 3D Designer runs as a desktop application, successful exploitation yields code execution with the privileges of the current user account.

The attack vector is local and interaction-based. An attacker must deliver a malicious .sbs, .sbsar, or related project asset to the target through email, chat, a shared repository, or a compromised website. The victim triggers the vulnerability by opening the file in a vulnerable version of Designer.

Root Cause

The defect stems from missing or insufficient bounds checking during file parsing. When Substance 3D Designer processes attacker-controlled structure fields, size or index values are not validated against the destination buffer capacity before a write operation. The parser then writes attacker-influenced bytes past the end of the buffer, corrupting heap metadata, function pointers, or virtual table references residing nearby.

Attack Vector

Exploitation follows a predictable social-engineering chain. The attacker prepares a malformed asset file, hosts or delivers it, and waits for the victim to double-click the file or open it from within Designer. No network exposure or authentication is required on the vulnerable host. The AV:L/UI:R conditions in the advisory reflect this local, user-triggered scenario. Refer to the Adobe Security Update APSB25-06 for parsing components and file types covered by the fix.

No public proof-of-concept has been observed for CVE-2025-21138, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2025-21138

Indicators of Compromise

Substance 3D Designer (Adobe Substance 3D Designer.exe) spawning unexpected child processes such as cmd.exe, powershell.exe, wscript.exe, or shell utilities on macOS.
Crashes or Windows Error Reporting (WER) entries referencing Substance 3D Designer immediately after opening a .sbs or .sbsar file from an untrusted source.
Newly written executables, DLLs, or scripts in the user profile directory shortly after a Substance 3D Designer session.

Detection Strategies

Monitor for process-creation events where the parent is Substance 3D Designer and the child is a scripting or command interpreter.
Alert on Substance 3D Designer opening files from download folders, email attachment cache directories, or removable media.
Track outbound network connections initiated by Substance 3D Designer to non-Adobe destinations, which is atypical for the application.

Monitoring Recommendations

Enable full command-line and process-lineage logging on workstations running Substance 3D Designer.
Ingest EDR telemetry into a central data lake and correlate Designer process events with file-open activity and network egress.
Maintain an inventory of Substance 3D Designer versions across endpoints to identify hosts still exposed to CVE-2025-21138.

How to Mitigate CVE-2025-21138

Immediate Actions Required

Upgrade Adobe Substance 3D Designer to the version specified in Adobe bulletin APSB25-06 on every workstation.
Instruct users to open Substance 3D asset files only from trusted internal sources or verified vendors.
Restrict local administrator rights on workstations that run creative tooling to limit the impact of user-context code execution.

Patch Information

Adobe addressed CVE-2025-21138 in the release documented in Adobe Security Update APSB25-06. Administrators should deploy the fixed build to all installations of Substance 3D Designer 14.0 and earlier. Verify version numbers through the application's About dialog or software inventory tooling after deployment.

Workarounds

Block execution of Substance 3D Designer through application control until the patched version is deployed if immediate patching is not feasible.
Quarantine or strip Substance 3D asset file types (.sbs, .sbsar) at the email gateway when originating from external senders.
Open untrusted 3D assets only inside an isolated virtual machine or dedicated sandbox host that has no access to sensitive resources.

bash

# Windows: report installed Substance 3D Designer version for audit
reg query "HKLM\SOFTWARE\Adobe\Substance 3D Designer" /s /v Version