Security readout for executives and security teams
Plain-English summary
This flaw lets a malicious file potentially run code when opened in Adobe InDesign. The main business risk is compromise of a designer or publisher workstation, not automatic network-wide exploitation. User interaction is required, but the impact is high because successful exploitation runs as the current user.
Executive priority
Treat this as a high-priority workstation patching issue for creative and publishing teams. It needs timely remediation, especially where employees routinely receive external files, but the evidence provided does not support emergency active-exploitation language.
Technical view
CVE-2021-21098 is a CWE-787 out-of-bounds write in Adobe InDesign 16.0 and earlier when parsing a crafted PCX file. It is unauthenticated, network-deliverable, requires user interaction, and has CVSS 3.1 score 8.8 with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely where Adobe InDesign 16.0 or earlier is installed and users open externally supplied design, image, or publishing files. Workstations handling client submissions, marketing assets, or archived creative files should be prioritized.
Exploitation context
The source bundle does not cite active exploitation, and KEV status is false. Exploitation requires persuading a victim to open a malicious file, so phishing, file-sharing workflows, or client-submitted assets are the plausible delivery paths.
Researcher notes
Key constraints are user interaction and current-user execution context. The bundle identifies the bug class and affected version boundary, but does not provide exploit details or exact fixed versions. Use Adobe’s advisory for authoritative remediation specifics.
Mitigation direction
- Review Adobe APSB21-22 and apply the vendor-recommended InDesign security update.
- Inventory endpoints for Adobe InDesign 16.0 or earlier.
- Restrict opening untrusted PCX or design files until patched.
- Use least-privilege user accounts for creative workstations.
- Route external creative files through malware scanning and sandbox review.
Validation and detection
- Confirm installed InDesign versions across managed endpoints.
- Check whether any systems still run InDesign 16.0 or earlier.
- Verify patch status against Adobe APSB21-22 guidance.
- Review endpoint alerts for suspicious child processes from InDesign.
- Confirm users handling external files receive targeted warning guidance.
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-2021-21098 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
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/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.
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:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://helpx.adobe.com/security/products/indesign/apsb21-22.htmlCVE reference · x_refsource_MISC
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.