Security readout for executives and security teams
Plain-English summary
CVE-2020-10021 is a high-severity memory corruption issue in Zephyr RTOS USB Mass Storage handling. A local actor able to interact with an affected device’s USB Mass Storage path may trigger an out-of-bounds write when sizes are unaligned. The sources do not show active exploitation.
Executive priority
Prioritize products where customers or untrusted users can physically access USB ports. This is high severity, but the provided evidence points to local access rather than remote internet exploitation. Treat remediation as important for exposed embedded devices, kiosks, labs, and field hardware.
Technical view
The flaw is a CWE-787 out-of-bounds write in the USB Mass Storage memoryWrite handler for unaligned sizes. The record lists Zephyr 1.14.1 and later, and 2.1.0 and later, as affected. CVSS 3.1 is 8.1 with local attack vector, high complexity, no privileges, no user interaction, changed scope, and high CIA impact.
Likely exposure
Most relevant exposure is embedded, IoT, or product firmware using Zephyr RTOS with USB Mass Storage enabled in the affected version ranges. Network-only services are not directly implicated by the provided sources. Teams should confirm whether shipped firmware includes this Zephyr component and feature.
Exploitation context
The CVSS vector indicates local access, high attack complexity, no privileges, and no user interaction. CISA KEV is false in the bundle, and no cited source reports active exploitation. Practical exploitability likely depends on physical or local USB interaction and product-specific USB Mass Storage configuration.
Researcher notes
Evidence identifies the vulnerable component, weakness class, CVSS vector, and affected Zephyr versions, but the bundle does not provide exact fixed release numbers. Use the Zephyr vulnerability page and linked PRs to verify patch lineage before making fleet-wide conclusions.
Mitigation direction
- Check Zephyr’s advisory and linked PRs for the applicable fixed branch or release.
- Upgrade affected Zephyr-based firmware when vendor-confirmed fixes are available.
- Disable USB Mass Storage functionality where it is not required.
- Restrict physical USB access on deployed affected devices where feasible.
- Ask device vendors for firmware advisories if Zephyr is bundled indirectly.
Validation and detection
- Inventory products and firmware builds using Zephyr RTOS.
- Confirm whether USB Mass Storage support is enabled in each build.
- Map firmware Zephyr versions against the affected records and vendor advisory.
- Review linked Zephyr pull requests for patched code presence.
- Document compensating controls for devices awaiting firmware updates.
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 lookupCVE-2020-10021 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
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/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:H/PR:N/UI:N/S:C/C:H/I:H/A:H1.46Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://zephyrprojectsec.atlassian.net/browse/ZEPSEC-26CVE reference · x_refsource_MISC
- https://github.com/zephyrproject-rtos/zephyr/pull/23240CVE reference · x_refsource_MISC
- https://github.com/zephyrproject-rtos/zephyr/pull/23455CVE reference · x_refsource_MISC
- https://github.com/zephyrproject-rtos/zephyr/pull/23456CVE reference · x_refsource_MISC
- https://docs.zephyrproject.org/latest/security/vulnerabilities.html#cve-2020-10021CVE 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.