Security readout for executives and security teams
Plain-English summary
A malicious file opened in Adobe Acrobat Reader DC could corrupt memory and run code as that user. The attacker does not need an account, but the victim must open the file. Business impact is highest where staff regularly handle external PDFs or attachments.
Executive priority
Prioritize remediation, especially for document-heavy teams. This is high severity because exploitation can execute code, but urgency is moderated by required user interaction and no confirmed active exploitation in the provided sources.
Technical view
CVE-2021-28642 is a CWE-787 out-of-bounds write in Adobe Acrobat Reader DC. CVSS 3.1 is 8.8: network attack vector, low complexity, no privileges required, and user interaction required. Successful exploitation can impact confidentiality, integrity, and availability in the current user context.
Likely exposure
Systems are likely exposed if they run Acrobat Reader DC 2021.005.20054 or earlier, 2020.004.30005 or earlier, or 2017.011.30197 or earlier. The source bundle also names Acrobat Pro DC in the title, but the affected product data specifically lists Acrobat Reader.
Exploitation context
The sources describe malicious-file exploitation requiring a victim to open the file. The bundle does not identify public exploit availability, observed exploitation, or CISA KEV listing. Treat active exploitation as unconfirmed from the provided evidence.
Researcher notes
The source bundle lacks root-cause detail, fixed build numbers, and exploit telemetry. Validate product scope carefully because the title mentions Acrobat Pro DC while affected data lists Acrobat Reader. Do not infer broader Adobe product exposure without vendor confirmation.
Mitigation direction
- Review Adobe APSB21-51 for fixed versions and deployment guidance.
- Update affected Acrobat Reader installations to a vendor-supported fixed release.
- Prioritize users who receive external PDFs or untrusted document attachments.
- Maintain email and web controls that reduce delivery of malicious documents.
Validation and detection
- Inventory Acrobat Reader DC versions across endpoints.
- Flag versions at or below the affected release numbers listed by CVE.
- Confirm update status against Adobe APSB21-51 guidance.
- Check whether high-risk user groups still run affected builds.
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-2021-28642 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/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.
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.