Security readout for executives and security teams
Plain-English summary
This flaw lets a malicious file trigger code execution in Adobe Acrobat Reader when a logged-in user opens it. Impact is serious because code runs as the current user, but exploitation requires user interaction and the provided sources do not show known active exploitation.
Executive priority
Treat as a high-priority endpoint patching issue, not an emergency zero-day based on this bundle. Remediate affected Reader installations promptly because successful exploitation could compromise user data and workstation integrity.
Technical view
CVE-2021-28640 is a CWE-416 use-after-free in Acrobat Reader DC 2021.005.20054 and earlier, 2020.004.30005 and earlier, and 2017.011.30197 and earlier. CVSS 3.1 is 7.3 with local attack vector, low complexity, low privileges, required user interaction, unchanged scope, and high CIA impact.
Likely exposure
Organizations are exposed where affected Acrobat Reader DC versions remain installed on endpoints, especially where users routinely open external PDF or document attachments. The bundle does not identify server-side exposure or affected Adobe products beyond Acrobat Reader.
Exploitation context
The sources state exploitation requires user interaction: a victim must open a malicious file. The bundle marks CISA KEV as false and provides no cited evidence of active exploitation, public exploitation, or weaponized campaigns.
Researcher notes
Evidence is limited to the CVE description, CVSS vector, KEV flag, and Adobe advisory reference. No exploit details, fixed version list, detection indicators, or proof of active exploitation are included in the supplied bundle.
Mitigation direction
- Inventory endpoints for affected Acrobat Reader DC versions.
- Review Adobe APSB21-51 and apply vendor-recommended updates or mitigations.
- Prioritize users who handle external documents or email attachments.
- Reinforce controls against opening untrusted files until remediation is complete.
Validation and detection
- Confirm installed Acrobat Reader versions against the affected version ranges.
- Verify endpoints have received the Adobe advisory remediation.
- Check vulnerability management scans for remaining CVE-2021-28640 findings.
- Review document-handling groups for higher-risk exposure.
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-2021-28640 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
- 7.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/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:L/UI:R/S:U/C:H/I:H/A:H1.35.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.3HighVector: CVSS:3.1/AV:L/AC:L/PR:L/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.