Security readout for executives and security teams
Plain-English summary
This Adobe Acrobat Reader DC issue can be triggered only if a user opens a malicious file. The supplied CVE data supports application denial-of-service from memory corruption, not confirmed data theft or system compromise. Business urgency is lower unless affected Reader versions remain broadly deployed.
Executive priority
Handle through normal patch management unless affected versions are widespread or used in high-risk workflows. The available evidence indicates low technical severity, user interaction required, and no confirmed active exploitation.
Technical view
CVE-2021-21046 is a CWE-787 memory corruption issue affecting Acrobat Reader DC 2020.013.20074 and earlier, 2020.001.30018 and earlier, and 2017.011.30188 and earlier. The CVSS vector is local, low complexity, no privileges, user interaction required, with low availability impact only.
Likely exposure
Exposure is most likely on endpoints running the listed Acrobat Reader DC versions, especially where users open PDFs or attachments from email, downloads, shared drives, or web sources.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Exploitation requires convincing a victim to open a malicious file, and the supplied impact data supports denial-of-service.
Researcher notes
There is a source tension: the title references arbitrary code execution, while the provided description and CVSS vector only support application denial-of-service. Treat code execution as unconfirmed from this bundle and rely on Adobe guidance for definitive remediation details.
Mitigation direction
- Inventory Acrobat Reader DC versions across managed endpoints.
- Review and apply Adobe APSB21-09 vendor update guidance.
- Prioritize endpoints handling external PDFs or email attachments.
- Limit user exposure to untrusted PDF files where practical.
- Maintain attachment filtering and user warnings for suspicious PDFs.
Validation and detection
- Confirm installed Reader versions are newer than affected release thresholds.
- Verify Adobe APSB21-09 guidance was applied successfully.
- Check software inventory for unmanaged or legacy Reader installations.
- Review endpoint telemetry for Reader crashes after suspicious PDF opens.
- Validate email and web controls flag suspicious PDF 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-787: 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-2021-21046 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
- Low
- CVSS
- 3.3 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
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:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L1.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
3.3LowVector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
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.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.