Security readout for executives and security teams
Plain-English summary
This is a Huawei HarmonyOS 2.0 availability bug. A flaw in the HwNearbyMain module can dereference a null pointer, causing a process restart. The public record rates it high because it is network-reachable, needs no authentication, and requires no user interaction, but the documented impact is denial of service, not data theft.
Executive priority
Treat this as a high-priority availability risk for HarmonyOS 2.0 environments, especially where device uptime matters. It is not documented as a confidentiality or integrity issue in the provided sources, so urgency should be driven by exposed inventory and operational impact.
Technical view
CVE-2021-39977 is CWE-476 in HarmonyOS 2.0 HwNearbyMain. The CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, indicating remote unauthenticated availability impact only. The source bundle does not describe affected subversions, vulnerable interfaces, proof-of-concept details, or a component-level workaround.
Likely exposure
Exposure appears limited to Huawei HarmonyOS 2.0 assets using the HwNearbyMain module. The sources do not identify other Huawei products, other HarmonyOS versions, or specific device models. Organizations need device and OS inventory to determine relevance.
Exploitation context
The source bundle does not cite active exploitation, and KEV status is false. Based on CVSS, exploitation is assessed as network-accessible with low complexity and no credentials or user interaction, but public sources here only state that successful exploitation may restart a process.
Researcher notes
Public detail is sparse. The record names HwNearbyMain, CWE-476, HarmonyOS 2.0, and process restart impact. It does not provide vulnerable code paths, affected builds, exploit indicators, or workaround details. Avoid assuming broader Huawei ecosystem exposure without vendor confirmation.
Mitigation direction
- Check Huawei’s November 2021 HarmonyOS security bulletin for the applicable vendor update.
- Update affected HarmonyOS 2.0 devices to a vendor-supported patched level.
- Confirm device-model applicability through Huawei support or official device advisories.
- Monitor affected fleets for unexpected HwNearbyMain or related process restarts.
- Document any accepted availability risk for devices that cannot be updated.
Validation and detection
- Inventory Huawei devices and identify any running HarmonyOS 2.0.
- Verify each relevant device’s security patch level against Huawei’s bulletin.
- Confirm whether HwNearbyMain is present on in-scope assets.
- Review endpoint or device logs for repeated process restarts.
- Track remediation evidence by device model, OS version, and patch date.
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
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ATT&CK lookup starting points
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CWE-476: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-39977 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://device.harmonyos.com/en/docs/security/update/security-bulletins-202111-0000001217889667CVE 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.
NULL Pointer Dereference
NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.