Security readout for executives and security teams
Plain-English summary
This flaw lets a malicious PDF potentially run code when opened in vulnerable Adobe Acrobat Reader versions. It is not remotely exploitable without user interaction, but successful exploitation could compromise the user’s workstation data and permissions.
Executive priority
Treat as high priority for endpoint patching, especially in document-heavy business units. The issue needs user interaction, but the impact can be full code execution as the current user.
Technical view
CVE-2021-28553 is a CWE-416 use-after-free in Acrobat Reader DC affecting 2021.001.20150 and earlier, 2020.001.30020 and earlier, and 2017.011.30194 and earlier. CVSS 3.0 is 8.8, reflecting network delivery, no privileges, required user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Organizations are exposed where users run affected Acrobat Reader DC versions and open PDFs from email, web downloads, portals, or file shares. Risk is highest for staff who routinely handle external documents.
Exploitation context
The bundle states exploitation requires a victim to open a malicious file. CISA KEV status is false in the provided data, and no cited source confirms active exploitation.
Researcher notes
The provided evidence names Acrobat Reader DC affected branches and CVSS details but does not provide exploit details or fixed version numbers. Use Adobe APSB21-29 as the authoritative vendor remediation source.
Mitigation direction
- Apply Adobe guidance from APSB21-29 for Acrobat Reader updates.
- Inventory Acrobat Reader DC versions across managed endpoints.
- Prioritize remediation for users receiving external PDFs.
- Restrict untrusted PDF handling where vulnerable versions remain.
- Maintain least-privilege user configurations to limit post-exploitation impact.
Validation and detection
- Confirm installed Reader versions exceed the affected version thresholds.
- Verify endpoint management shows successful Acrobat Reader update deployment.
- Review exposure for users handling external or unsolicited PDFs.
- Check security telemetry for suspicious PDF-open events around affected endpoints.
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-2021-28553 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 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/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:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.8HighVector: CVSS:3.0/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.