CVE-2021-39998Network attack vector

System crash and reboot via concurrent API calls

Published Jan 7, 2022 · Updated Aug 4, 2024

Denial of service in affected Huawei EMUI, Magic UI, and HarmonyOS releases allows attackers to crash and reboot smartphones via concurrent API calls. HwConnectivityExService permits its APIs to be invoked concurrently multiple times, and that repeated concurrency triggers the system crash and restart. Huawei has not published the caller privileges or reachability required to invoke the APIs; the documented consequence is limited to service interruption by crash and reboot.

CVSS severity7.5
High
EPSS probability0.70%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in affected Huawei EMUI, Magic UI, and HarmonyOS releases allows attackers to crash and reboot smartphones via concurrent API calls. HwConnectivityExService permits its APIs to be invoked concurrently multiple times, and that repeated concurrency triggers the system crash and restart. Huawei has not published the caller privileges or reachability required to invoke the APIs; the documented consequence is limited to service interruption by crash and reboot.

The record

CVE
CVE-2021-39998
Published
Jan 7, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1642
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 7, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.8NVDAV:N/AC:L/Au:N/C:N/I:N/A:C
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1642Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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