Security readout for executives and security teams
Plain-English summary
CVE-2021-28641 is a high-severity Adobe Acrobat Reader flaw. A malicious PDF or similar file could run code as the user who opens it. It requires user interaction, so the business risk is document-based compromise through phishing, downloads, or externally supplied files.
Executive priority
Treat this as a high-priority endpoint patching issue, not an internet-facing emergency. The main business risk is user-driven compromise through malicious documents. Prioritize exposed staff and legacy Acrobat Reader installations, and confirm Adobe remediation has been applied.
Technical view
The vulnerability is a use-after-free issue in Acrobat Reader DC 2021.005.20054 and earlier, 2020.004.30005 and earlier, and 2017.011.30197 and earlier. CVSS 3.1 is 7.8: local attack vector, low complexity, no privileges required, user interaction required, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely on endpoints where affected Acrobat Reader versions remain installed, especially users who open external PDFs, email attachments, downloaded documents, or files from third parties. Servers are less directly exposed unless they process documents interactively under user context.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. Exploitation requires a victim to open a malicious file, making phishing and document delivery the relevant threat path. The impact is arbitrary code execution in the current user's context.
Researcher notes
Evidence supports affected versions, CWE-416 use-after-free classification, CVSS 7.8, and user-interaction requirements. The bundle does not provide exploit availability, exploit maturity, or detailed patch metadata. Do not assert active exploitation from these sources alone.
Mitigation direction
- Apply Adobe guidance from APSB21-51 or the current vendor-supported Acrobat Reader update.
- Remove or upgrade Acrobat Reader versions at or below the listed affected builds.
- Limit opening of untrusted PDFs from email, web downloads, and external file shares.
- Use endpoint controls to reduce impact from document-launched code execution.
- Prioritize users with high document exposure or elevated local privileges.
Validation and detection
- Inventory Acrobat Reader versions across managed endpoints.
- Compare installed builds against the affected version thresholds in the CVE description.
- Confirm patch deployment status against Adobe APSB21-51 or current Adobe guidance.
- Review endpoint telemetry for suspicious document-opening chains, without assuming confirmed exploitation.
- Verify high-risk users are covered by email and attachment security controls.
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-2021-28641 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/apsb21-51.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.