Security readout for executives and security teams
Plain-English summary
This flaw lets a malicious PDF-like file abuse Adobe Acrobat Reader DC path handling to run code as the person who opens it. It is serious because the attacker does not need an account, but the victim must open a malicious file.
Executive priority
Treat as high priority for desktop patching, especially where staff regularly receive external PDFs. It is not described as actively exploited in the bundle, but arbitrary code execution from a user-opened file creates meaningful business risk.
Technical view
CVE-2021-21037 is a CWE-22 path traversal issue in Acrobat Reader DC versions 2020.013.20074 and earlier, 2020.001.30018 and earlier, and 2017.011.30188 and earlier. CVSS 3.1 is 7.8: local attack vector, low complexity, no privileges, user interaction required, high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is primarily managed and unmanaged desktops where affected Adobe Acrobat Reader DC versions can open untrusted files, including email attachments, downloads, and shared documents.
Exploitation context
The bundle does not show KEV listing or active exploitation evidence. Exploitation requires user interaction: a victim must open a malicious file. Successful exploitation runs code in the current user's context.
Researcher notes
Evidence is limited to CVE metadata and Adobe advisory reference. The record identifies path traversal and arbitrary code execution, but does not provide root-cause detail, exploit artifacts, or a named mitigation beyond vendor guidance.
Mitigation direction
- Inventory Acrobat Reader DC versions across endpoints.
- Apply Adobe APSB21-09 guidance or current vendor updates.
- Reduce exposure to untrusted attachments and downloads.
- Run Acrobat Reader with least-privilege user accounts where possible.
Validation and detection
- Compare installed versions against affected version thresholds.
- Confirm endpoints received the relevant Adobe security update.
- Review software inventory for unmanaged Acrobat Reader installations.
- Check endpoint controls for handling untrusted document attachments.
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-22: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. 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 lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-21037 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/apsb21-09.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.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.