Security readout for executives and security teams
Plain-English summary
This vulnerability affects older Adobe Acrobat Reader releases. A malicious PDF or similar file could cause Reader to disclose sensitive information accessible to the current user. It does not indicate system takeover, but exposure matters where staff handle confidential documents.
Executive priority
Treat as a medium-priority endpoint remediation item. It is not described as code execution, but could expose sensitive information through malicious files opened by users.
Technical view
CVE-2021-28555 is a CWE-125 out-of-bounds read in Acrobat Reader DC 2021.001.20150 and earlier, 2020.001.30020 and earlier, and 2017.011.30194 and earlier. CVSS 3.0 is 6.5, with network attack vector, no privileges, required user interaction, and high confidentiality impact.
Likely exposure
Organizations are exposed if they still run the listed Acrobat Reader DC tracks at or below the affected versions, especially on endpoints used for email attachments, downloads, or sensitive document handling.
Exploitation context
The supplied sources require user interaction: a victim must open a malicious file. The source bundle does not indicate CISA KEV listing or provide evidence of active exploitation.
Researcher notes
Key constraints are confidentiality-only CVSS impact, required user interaction, and current-user context. The bundle does not provide exploit details, patch version specifics, or active exploitation evidence.
Mitigation direction
- Inventory Adobe Acrobat Reader versions across managed endpoints.
- Check Adobe APSB21-29 for vendor-approved update guidance.
- Update or remove affected Reader versions where present.
- Reduce handling of unexpected PDF files from untrusted sources.
- Prioritize endpoints used for sensitive documents or external email.
Validation and detection
- Confirm installed Reader versions are not at or below affected releases.
- Verify remediation status against Adobe APSB21-29 guidance.
- Review asset inventory for unmanaged Acrobat Reader installations.
- Check security telemetry for suspicious document-open events if available.
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-125: 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 lookupCVE-2021-28555 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
- Medium
- CVSS
- 6.5 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
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:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N2.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
6.5MediumVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
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.
Out-of-bounds Read
Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.