CVE-2021-3969

SYSTEM privilege escalation via signed-DLL replacement race

Published May 18, 2022 · Updated Aug 3, 2024

TOCTOU in Lenovo IMController before 1.1.20.3 allows local users to execute attacker-controlled DLL code with SYSTEM privileges. Its privileged child process releases the signed plugin DLL after signature validation, allowing replacement before the later load. Exploitation requires local low-privileged access, writable files, and control of a plugin-load request, supplied in the published chain by a companion named-pipe race.

CVSS severity7.8
High
EPSS probability1.93%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TOCTOU in Lenovo IMController before 1.1.20.3 allows local users to execute attacker-controlled DLL code with SYSTEM privileges. Its privileged child process releases the signed plugin DLL after signature validation, allowing replacement before the later load. Exploitation requires local low-privileged access, writable files, and control of a plugin-load request, supplied in the published chain by a companion named-pipe race.

The record

CVE
CVE-2021-3969
Published
May 18, 2022
Updated
Aug 3, 2024
Vendor
Lenovo
Product
Lenovo IMController
Classifications
CWE-367, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 18, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=unspecified <1.1.20.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Lenovo · Lenovo IMControllerversion=unspecified <1.1.20.3

Published CVSS scores

7.8Lenovo Group Ltd.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.4NIST NVDAV:L/AC:M/Au:N/C:P/I:P/A:P
7.1NCC GroupCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:U/RC:R
7.0NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1068Exploitation for Privilege Escalation

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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