CVE-2021-39658

Local privilege escalation via unchecked service requests

Published Feb 11, 2022 · Updated Aug 4, 2024

Improper authorization in UNISOC ismsEx Service on Android SoCs allows local users to modify system properties through a third-party app. The SMS-extension service accepts requests from third-party applications without checking the caller's permissions before writing system properties. A locally installed application needs no granted permission or user interaction, enabling unauthorized changes to security-relevant device configuration.

CVSS severity9.8
Critical
EPSS probability0.57%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authorization in UNISOC ismsEx Service on Android SoCs allows local users to modify system properties through a third-party app. The SMS-extension service accepts requests from third-party applications without checking the caller's permissions before writing system properties. A locally installed application needs no granted permission or user interaction, enabling unauthorized changes to security-relevant device configuration.

The record

CVE
CVE-2021-39658
Published
Feb 11, 2022
Updated
Aug 4, 2024
Vendor
UNISOC
Product
ismsEx Service
Classifications
CWE-276, T1626
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 11, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Android SoC

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

UNISOC · ismsEx Serviceversion=Android SoC

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0NIST NVDAV:N/AC:L/Au:N/C:C/I:C/A:C

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-276Incorrect Default Permissions
T1626Abuse Elevation Control Mechanism

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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