Security readout for executives and security teams
Plain-English summary
This is a high-severity Adobe Acrobat Reader flaw that could let a malicious document run code on a user’s workstation. The attacker does not need credentials, but the victim must open the malicious file. Business risk is highest where users handle external PDFs.
Executive priority
Treat as a priority endpoint patching issue, not a server emergency. The impact is severe if exploited, but the available evidence here requires victim file opening and does not confirm active exploitation.
Technical view
CVE-2021-28562 is a CWE-416 use-after-free in Acrobat Reader JavaScript search-query handling. A crafted file can trigger arbitrary code execution as the current user. CVSS 3.1 is 8.8: network attack vector, low complexity, no privileges required, user interaction required, high confidentiality, integrity, and availability impact.
Likely exposure
Organizations with Adobe Acrobat Reader DC 2021.001.20150 and earlier, 2020.001.30020 and earlier, or 2017.011.30194 and earlier are potentially exposed, especially on endpoints receiving external PDFs.
Exploitation context
The source bundle does not show CISA KEV listing or confirmed active exploitation. Exploitation requires user interaction: a victim must open a malicious file that reaches the vulnerable JavaScript search-query path.
Researcher notes
Validate exposure by exact Acrobat Reader track and version. The vulnerability is client-side code execution through JavaScript search-query handling. Evidence in the bundle is limited to affected version thresholds, CVSS, CWE, user-interaction requirement, and Adobe advisory reference.
Mitigation direction
- Check Adobe APSB21-29 for the fixed release for each Acrobat Reader track.
- Update affected Acrobat Reader installations through approved enterprise software management.
- Prioritize users who routinely handle external or unsolicited PDF files.
- Use existing email, web, and endpoint controls to reduce malicious document delivery.
- Do not treat user training as a substitute for updating affected software.
Validation and detection
- Inventory Acrobat Reader versions across managed endpoints.
- Flag Reader DC versions at or below the listed affected builds.
- Confirm whether deployed versions align with Adobe APSB21-29 guidance.
- Review security tooling for suspicious PDF-open events around exposed users.
- Document exceptions where affected Reader versions cannot be updated promptly.
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-2021-28562 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/apsb21-29.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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.