CVE-2021-39986Public exploit

Secure-world memory disclosure via writable LPMCU firmware

Published Feb 9, 2022 · Updated Aug 4, 2024

Authorization bypass in Huawei EMUI 12.0.0 allows attackers to read protected Secure World memory from the baseband. The DMSS fails to block modem writes to LPMCU firmware in SRAM, allowing patched LPMCU code to rewrite DMSS ASI permission entries. Exploitation requires code execution on the baseband; successful permission rewrites expose memory belonging to every SoC core, including Secure World.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Huawei EMUI 12.0.0 allows attackers to read protected Secure World memory from the baseband. The DMSS fails to block modem writes to LPMCU firmware in SRAM, allowing patched LPMCU code to rewrite DMSS ASI permission entries. Exploitation requires code execution on the baseband; successful permission rewrites expose memory belonging to every SoC core, including Secure World.

The record

CVE
CVE-2021-39986
Published
Feb 9, 2022
Updated
Aug 4, 2024
Vendor
MindSpore
Product
EMUI
Classifications
T1404
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 9, 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=12.0.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

MindSpore · EMUIversion=12.0.0

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
2.1NIST NVDAV:L/AC:L/Au:N/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1404Exploitation for Privilege Escalation

Public exploit references

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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