Security readout for executives and security teams
Plain-English summary
This is a critical Huawei mobile OS vulnerability in HW_KEYMASTER. An unauthenticated network attacker could send maliciously constructed data that triggers out-of-bounds access during parameter verification. The published impact includes high confidentiality and integrity risk, with no availability impact stated.
Executive priority
Treat this as a high-priority mobile platform exposure if Huawei devices are in scope. The business urgency depends on fleet presence, but affected devices should be patched or removed from trusted access paths promptly because the vulnerability is remote and unauthenticated.
Technical view
CVE-2021-46840 is a CWE-125 out-of-bounds access issue in HW_KEYMASTER parameter-set verification affecting HarmonyOS 2.0 and EMUI 12.0.0/11.0.1. CVSS v3.1 is 9.1: network attack vector, low complexity, no privileges, and no user interaction.
Likely exposure
Exposure is limited to Huawei devices running HarmonyOS 2.0 or EMUI 12.0.0/11.0.1. Organizations with managed Huawei phones, BYOD Huawei devices, or region-specific Huawei fleets should verify operating system versions and vendor security patch status.
Exploitation context
The provided sources do not state active exploitation, and the CVE is not marked as CISA KEV in the bundle. The risk remains serious because the CVSS vector indicates remote, unauthenticated exploitation with low complexity and no user interaction.
Researcher notes
Public detail is sparse. The bundle identifies the module, bug class, affected OS versions, and CVSS vector, but does not provide exploit mechanics, fixed-build granularity, or evidence of exploitation. Validation should focus on version exposure and vendor bulletin mapping.
Mitigation direction
- Review Huawei's October 2022 security bulletins for affected and fixed device builds.
- Apply Huawei-provided security updates to affected HarmonyOS and EMUI devices.
- Prioritize managed or privileged-user devices running the listed versions.
- Restrict or retire devices that cannot receive applicable Huawei updates.
- Monitor Huawei guidance for any revised affected-version or fix information.
Validation and detection
- Inventory Huawei devices and record HarmonyOS or EMUI versions.
- Compare device builds against Huawei's October 2022 bulletin guidance.
- Confirm patched devices are no longer running affected listed versions.
- Check mobile device management records for unmanaged Huawei devices.
- Document exceptions where update status cannot be confirmed.
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-125: 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-2021-46840 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
- Critical
- CVSS
- 9.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:N/UI:N/S:U/C:H/I:H/A:N3.95.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.1CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Source materials
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 Read
Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.