CVE-2021-36924

Local privilege escalation via IOCTL TOCTOU overflow

Published Nov 2, 2021 · Updated Aug 4, 2024

Pool overflow in Realtek RtsUpx USB Utility Driver 1.14.0.0 and earlier allows local users to execute code with elevated privileges. The RtsUpx.sys IOCTL path does not safely validate user-mode input across a time-of-check to time-of-use sequence, causing a pool overflow. Low-privilege local access and a crafted Device IO Control packet are required; successful exploitation can also crash the system.

CVSS severity7.8
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Pool overflow in Realtek RtsUpx USB Utility Driver 1.14.0.0 and earlier allows local users to execute code with elevated privileges. The RtsUpx.sys IOCTL path does not safely validate user-mode input across a time-of-check to time-of-use sequence, causing a pool overflow. Low-privilege local access and a crafted Device IO Control packet are required; successful exploitation can also crash the system.

The record

CVE
CVE-2021-36924
Published
Nov 2, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-367, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 2, 2021CVE 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 vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.8NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.2NIST National Vulnerability DatabaseAV:L/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.

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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