Security readout for executives and security teams
CVE-2021-3861 is a high-severity heap buffer overflow in Zephyr's RNDIS USB device class. Products using the affected Zephyr RNDIS USB functionality could suffer data integrity or availability impact. The source bundle does not name active exploitation or a specific patched version. Likely exposure is embedded or IoT firmware that includes Zephyr v2.6.0 or later as described, and enables the RNDIS USB device class. Exposure cannot be confirmed from package names alone; firmware configuration and component use matter. Prioritize products where USB networking is enabled and devices are physically accessible to untrusted users. The issue is high severity, but the available evidence does not show internet-scale or confirmed active exploitation. Mitigation focus: Check the Zephyr advisory for fixed versions and vendor guidance.; Inventory firmware using Zephyr RNDIS USB device class.; Upgrade affected Zephyr builds when a vendor-supported fix is available..
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
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ATT&CK lookup starting points
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Open ATT&CK lookupCVE-2021-3861 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 8.2 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
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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:A/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:H1.66Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.2HighVector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
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.
Heap-based Buffer Overflow
Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.