Security readout for executives and security teams
Plain-English summary
This flaw lets a malicious PDF potentially run code when opened in affected Adobe Acrobat Reader versions. It does not require attacker login, but it does require the user to open the file. Business urgency is high for organizations with broad Reader deployment and email or download-based PDF workflows.
Executive priority
Treat as high priority for endpoint patching. The impact is full user-context code execution, but the attack depends on a user opening a malicious PDF and current sources do not confirm active exploitation.
Technical view
CVE-2021-28558 is a heap-based buffer overflow in Adobe Acrobat Reader DC's PDFLibTool component. Affected versions include 2021.001.20150 and earlier, 2020.001.30020 and earlier, and 2017.011.30194 and earlier. Successful exploitation could execute code as the current user. CVSS is 8.8, CWE-122.
Likely exposure
Exposure is likely on workstations running affected Adobe Acrobat Reader DC versions, especially where users routinely open PDFs from email, web downloads, shared drives, or external parties.
Exploitation context
The provided sources do not show CISA KEV listing or confirmed active exploitation. Exploitation requires user interaction: a victim must open a malicious file. The attacker does not need authentication.
Researcher notes
Evidence is limited to the CVE record and Adobe advisory reference. Validate product lineage carefully because the source names Acrobat Reader DC versions, not every Adobe PDF product. Do not assume exploit availability or additional affected products from this bundle.
Mitigation direction
- Inventory Adobe Acrobat Reader versions across managed endpoints.
- Apply Adobe's security update or guidance from APSB21-29.
- Prioritize endpoints handling external PDFs or email attachments.
- Limit users' ability to open untrusted PDFs where practical.
- Use least-privilege user accounts to reduce impact.
Validation and detection
- Confirm installed Reader versions against Adobe's affected version list.
- Verify updated endpoints are no longer at affected versions.
- Check patch management reports for Reader coverage gaps.
- Review mail and web controls for untrusted PDF handling.
- Document any unsupported Reader versions requiring replacement.
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-122: 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-2021-28558 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.
Heap-based Buffer Overflow
Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.