Security readout for executives and security teams
Plain-English summary
Adobe Substance 3D Designer 15.0.3 and earlier can execute attacker-controlled code when a user opens a malicious file. Successful exploitation could expose data, alter files, or disrupt the user’s system with that user’s permissions. The supplied sources do not establish active exploitation.
Executive priority
Prioritize remediation for creative teams handling external assets. The potential impact is complete compromise of the current user’s data and workstation activity, although exploitation requires a malicious file to be opened. Address exposed systems promptly through normal high-severity patching processes.
Technical view
CVE-2026-21307 is an out-of-bounds write (CWE-787) rated CVSS 7.8. It requires local delivery and user interaction but no prior privileges. A crafted file may trigger arbitrary code execution in the current user’s context, affecting confidentiality, integrity, and availability.
Likely exposure
Exposure is most likely on workstations running Substance 3D Designer 15.0.3 or earlier, especially where users receive project files from external or untrusted sources. The bundle’s structured version data mentions 15.1.0, but its description explicitly identifies 15.0.3 and earlier; confirm applicability with Adobe.
Exploitation context
A victim must open a malicious file. The attack is therefore suited to phishing, compromised collaboration channels, or untrusted downloaded assets. The CVE is not listed as KEV in the supplied bundle, and no supplied source confirms public exploitation or exploit availability.
Researcher notes
The CVSS vector is AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. The supplied description says 15.0.3 and earlier, while structured affected data references 15.1.0 with default status unaffected. Treat the precise boundary as requiring confirmation from Adobe. No root cause detail beyond CWE-787 is supplied.
Mitigation direction
- Inventory Substance 3D Designer installations and identify versions 15.0.3 or earlier.
- Review Adobe’s advisory and apply its specified update or remediation.
- Until remediated, restrict opening Substance files from untrusted or unexpected sources.
- Use endpoint controls to limit the impact of code executing with user permissions.
Validation and detection
- Confirm installed Designer versions through software inventory or endpoint management records.
- Verify remediated systems match the version specified in Adobe’s advisory.
- Check endpoint telemetry for suspicious activity following Designer file-open events.
- Confirm controls warn about or block files received from untrusted sources.
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-787: 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-21307 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_designer/apsb26-13.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 Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.