Security readout for executives and security teams
Plain-English summary
CVE-2021-23881 is a stored cross-site scripting flaw in McAfee Endpoint Security for Windows ePO extension. A privileged ePO administrator could place script content in a policy event, which later runs in a user’s browser block page when a local non-administrator triggers that policy.
Executive priority
Treat as moderate priority. It is not described as actively exploited and requires privileged access, but it could turn an abused ePO admin account into browser-based impact on endpoint users.
Technical view
The issue is CWE-79 stored XSS affecting McAfee Endpoint Security (ENS) for Windows 10.7.x before the 10.7.0 February 2021 Update. CVSS 3.1 is 4.8: network attack vector, low complexity, high privileges required, user interaction required, changed scope, low confidentiality and integrity impact, no availability impact.
Likely exposure
Exposure is likely limited to organizations running affected McAfee ENS for Windows with ePO extension versions before the February 2021 update. The attack path depends on high-privilege ePO administrative access and a local user triggering the relevant policy.
Exploitation context
The provided sources do not identify active exploitation, and the CVE is not marked KEV. Practical exploitation requires an ENS ePO administrator role or equivalent compromise, plus user interaction through a browser block page.
Researcher notes
Evidence is limited to the CVE record, CVE List data, and McAfee advisory reference. Validation should focus on affected ENS/ePO extension versions, policy event storage, and administrative change history, without assuming broader products or exploit availability.
Mitigation direction
- Update McAfee ENS for Windows to the 10.7.0 February 2021 Update or later.
- Review McAfee advisory SB10345 for exact vendor remediation guidance.
- Restrict and audit ePO administrator privileges.
- Inspect policy events for unexpected script-like content.
Validation and detection
- Inventory ENS for Windows versions and confirm affected 10.7.x systems.
- Verify the ePO extension update level against the February 2021 update.
- Review ePO policy event fields for suspicious embedded scripts.
- Check logs for unusual policy changes by administrator accounts.
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-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. 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 lookupCVE-2021-23881 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
- Medium
- CVSS
- 4.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
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:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N1.72.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.8MediumVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://kc.mcafee.com/corporate/index?page=content&id=SB10345CVE reference · x_refsource_CONFIRM
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.