Security readout for executives and security teams
Plain-English summary
A malicious file opened in Adobe Substance 3D Stager could exploit a memory-reading flaw and potentially run code with the victim’s permissions. Successful exploitation requires user interaction, but the possible impact includes loss of confidentiality, integrity, and availability.
Executive priority
Prioritize remediation on creative workstations that exchange files externally or handle untrusted content. Treat this as a high-priority endpoint update, while recognizing that exploitation requires a user to open a crafted file and active exploitation is not established by the supplied evidence.
Technical view
CVE-2026-21345 is a CWE-125 out-of-bounds read in Substance 3D Stager 3.1.6 and earlier. Parsing a crafted file may read beyond an allocated memory structure and potentially enable code execution as the current user. CVSS 3.1 is 7.8: local attack vector, low complexity, no privileges, and required user interaction.
Likely exposure
Exposure is concentrated on endpoints running Substance 3D Stager 3.1.6 or earlier, particularly where users receive or open files from external or untrusted sources. The source bundle does not identify server-side or remote, interaction-free exposure.
Exploitation context
Exploitation requires convincing a user to open a malicious file. The source bundle marks this CVE as absent from KEV and provides no evidence of active exploitation. That absence does not establish that exploitation is impossible or has never occurred.
Researcher notes
The affected-version description states 3.1.6 and earlier. The structured affected data also contains 3.1.7 with default status unaffected, suggesting a boundary, but its encoding is ambiguous. Confirm exact fixed and affected builds in Adobe’s advisory. No exploit mechanics or active campaign evidence are present in the bundle.
Mitigation direction
- Inventory Substance 3D Stager installations and identify versions 3.1.6 or earlier.
- Follow Adobe’s advisory for the supported update or remediation applicable to each installation.
- Restrict opening untrusted Stager-compatible files until affected systems are remediated.
- Use endpoint controls and least privilege to reduce impact from user-context code execution.
Validation and detection
- Confirm installed Substance 3D Stager versions using endpoint or software inventory records.
- Verify affected installations were updated according to Adobe’s advisory.
- Review endpoint telemetry for suspicious activity following Stager opening externally sourced files.
- Confirm file-handling controls cover untrusted files delivered through email, downloads, and collaboration platforms.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-125: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-21345 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H1.85.9adobeVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://helpx.adobe.com/security/products/substance3d_stager/apsb26-20.htmlCVE reference, adobe · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Read
Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.