Security readout for executives and security teams
Plain-English summary
This flaw lets a malicious PDF trigger code execution when a user opens it in affected Adobe Acrobat Reader DC versions. The attacker does not need credentials, but needs user interaction. Business risk is highest on endpoints where users receive untrusted PDF files.
Executive priority
Treat as a high-priority endpoint patching issue, not an internet-facing emergency. The main business risk is phishing or document-based compromise of users who open malicious PDFs.
Technical view
CVE-2021-28552 is a CWE-416 use-after-free issue in Adobe Acrobat Reader DC, described as XFA Template-related RCE. CVSS is 7.8: local attack vector, low complexity, no privileges, user interaction required, with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely on workstations running Acrobat Reader DC 2021.001.20155 or earlier, 2020.001.30025 or earlier, or 2017.011.30196 or earlier, especially where PDFs arrive by email, web download, or document workflows.
Exploitation context
The provided sources do not show active exploitation or CISA KEV listing. Exploitation requires a victim to open a malicious file, and successful exploitation runs code as the current user rather than directly as system.
Researcher notes
Evidence supports RCE through a use-after-free with required user interaction. The bundle does not include proof-of-concept details, exploitation-in-the-wild evidence, or fixed version numbers, so remediation should be tied directly to Adobe’s bulletin.
Mitigation direction
- Inventory Acrobat Reader DC versions across managed endpoints.
- Apply Adobe guidance from APSB21-29 or current vendor update channels.
- Prioritize users handling external PDFs or high-value documents.
- Reduce exposure to untrusted PDF attachments where practical.
- Use endpoint controls to detect suspicious PDF-spawned processes.
Validation and detection
- Confirm installed Reader versions are newer than the affected version thresholds.
- Review software inventory for 2017, 2020, and 2021 Reader tracks.
- Check Adobe APSB21-29 for the applicable fixed release path.
- Validate endpoint telemetry for unusual child processes from Reader.
- Confirm vulnerable versions are not present on high-risk user groups.
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-416: 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-2021-28552 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.
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:H1.85.9Primary CVE scoreVulnerability 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
Source materials
- CVE List V5 sourceCVE List V5
- https://helpx.adobe.com/security/products/acrobat/apsb21-29.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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.