Security readout for executives and security teams
Plain-English summary
This flaw can let a malicious PDF run code as the person who opens it in Adobe Acrobat Reader DC. It is serious for organizations that handle unsolicited PDFs, but exploitation requires user interaction and no provided source confirms active exploitation.
Executive priority
Treat as a high-priority workstation patching issue, especially for teams exposed to external documents. Business urgency is elevated by code execution impact, but tempered by required user interaction and no confirmed active exploitation in the provided evidence.
Technical view
CVE-2021-35981 is a CWE-416 use-after-free in Acrobat Reader DC launchURL handling. Affected versions include 2021.005.20054 and earlier, 2020.004.30005 and earlier, and 2017.011.30197 and earlier. Successful exploitation enables arbitrary code execution as the current user after opening a malicious file.
Likely exposure
Exposure is most likely on desktops, VDI images, or unmanaged endpoints running affected Acrobat Reader DC tracks and regularly opening PDFs from email, web downloads, client portals, or file shares.
Exploitation context
The source bundle says exploitation requires a victim to open a malicious file. KEV is false, and the provided sources do not establish active exploitation or public weaponization.
Researcher notes
Evidence is limited to the CVE record and Adobe advisory reference. The exact fixed versions and technical root-cause details are not included in the bundle, so validation should focus on version exposure and Adobe APSB21-51 alignment.
Mitigation direction
- Inventory Acrobat Reader DC versions across endpoints and VDI images.
- Check Adobe APSB21-51 for the vendor-approved update path.
- Prioritize systems that receive external PDFs or handle sensitive data.
- Use email and web controls to reduce delivery of untrusted PDFs.
- Limit user privileges so Reader compromise has reduced impact.
Validation and detection
- Identify hosts running 2021.005.20054 or earlier.
- Identify hosts running 2020.004.30005 or earlier.
- Identify hosts running 2017.011.30197 or earlier.
- Confirm Adobe Reader updates completed successfully on exposed endpoint groups.
- Review security telemetry for suspicious PDF activity on vulnerable hosts.
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-2021-35981 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.