Security readout for executives and security teams
Plain-English summary
CVE-2021-35983 is a high-impact Adobe Acrobat Reader flaw. A malicious PDF-like file could execute code as the logged-in user if opened. This creates business risk through phishing, document exchange, and unmanaged endpoints, but the provided sources do not show confirmed active exploitation.
Executive priority
Treat as a near-term endpoint patching priority. The issue needs user interaction, but document-based attacks are common and successful exploitation can compromise the user's workstation permissions.
Technical view
Adobe describes a use-after-free vulnerability in Acrobat Reader DC AcroForm handling. A local user action is required: the victim must open a malicious file. Successful exploitation allows arbitrary code execution in the current user's context. CVSS 3.1 is 7.8 with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely on endpoints running Acrobat Reader DC 2021.005.20054 or earlier, 2020.004.30005 or earlier, or 2017.011.30197 or earlier, especially where users receive external documents.
Exploitation context
The source bundle states exploitation requires user interaction and no privileges. CISA KEV status is false in the provided data, so active exploitation is not established by these sources.
Researcher notes
Evidence supports RCE through CWE-416 use-after-free in AcroForm processing. The provided sources do not include proof-of-concept details, indicators, or confirmed exploitation. Avoid assuming broader Adobe products are affected beyond the listed Acrobat Reader DC versions.
Mitigation direction
- Apply Adobe updates referenced in APSB21-51 for affected Acrobat Reader versions.
- Inventory endpoints for Acrobat Reader DC 2021, 2020, and 2017 tracks.
- Prioritize users handling external PDFs, invoices, contracts, or applicant documents.
- Use vendor guidance if an endpoint cannot be immediately updated.
- Restrict opening untrusted files on vulnerable systems until remediated.
Validation and detection
- Check installed Acrobat Reader versions against the affected version thresholds.
- Confirm patched versions align with Adobe APSB21-51 guidance.
- Verify software inventory covers remote, unmanaged, and contractor endpoints.
- Review email and web controls for untrusted document handling.
- Document any compensating controls for systems awaiting updates.
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-2021-35983 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/apsb21-51.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.