Security readout for executives and security teams
Plain-English summary
This vulnerability can let a malicious PDF-like file run code as the signed-in user when opened in affected Adobe Acrobat Reader DC versions. It is serious because it targets common desktop software, but the source bundle requires user interaction and does not show confirmed active exploitation.
Executive priority
Treat this as a high-priority workstation patching issue, not an internet-facing emergency. Prioritize high-risk document-handling users and complete Adobe update validation because successful exploitation can compromise the current user’s data and workstation.
Technical view
CVE-2021-28551 is a CWE-125 out-of-bounds read in affected Adobe Acrobat Reader DC versions. Adobe and CVE describe potential arbitrary code execution in the current user context after a victim opens a malicious file. CVSS 3.1 is 7.8, with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely on workstations running Acrobat Reader DC 2021.001.20155 or earlier, 2020.001.30025 or earlier, or 2017.011.30196 or earlier, especially users who receive external documents by email, web download, or file sharing.
Exploitation context
The source bundle does not cite active exploitation, and CISA KEV is false. Exploitation requires a victim to open a malicious file. No exploit details or public weaponization evidence are provided in the supplied sources.
Researcher notes
The available bundle identifies CWE-125 and RCE impact but does not include root-cause details, affected CPEs, fixed version numbers, or exploit telemetry. Analysis should stay anchored to Adobe APSB21-29 and CVE metadata until more vendor detail is reviewed.
Mitigation direction
- Update affected Adobe Acrobat Reader DC installations using Adobe APSB21-29 guidance.
- Prioritize systems used to open external PDFs or untrusted documents.
- Restrict handling of unsolicited documents until affected versions are updated.
- Use endpoint controls to reduce impact from user-context code execution.
Validation and detection
- Inventory installed Acrobat Reader DC versions across endpoints.
- Flag versions 2021.001.20155 and earlier, 2020.001.30025 and earlier, and 2017.011.30196 and earlier.
- Confirm Adobe APSB21-29 updates are applied where applicable.
- Review endpoint alerts involving suspicious document opens or Acrobat child processes.
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 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-2021-28551 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.
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.