CVE-2021-34413

Local privilege escalation via installer directory race

Published Sep 27, 2021 · Updated Aug 4, 2024

TOCTOU in the Zoom Plugin for Microsoft Outlook for macOS before 5.3.52553.0918 allows local users to gain elevated execution. During installation, the installer checks the plugin directory and later uses it after a standard user can replace its contents with a malicious application. Exploitation requires local standard-user access and execution of the plugin installer; the substituted application then runs in the installer's privileged context.

CVSS severity7.5
High
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TOCTOU in the Zoom Plugin for Microsoft Outlook for macOS before 5.3.52553.0918 allows local users to gain elevated execution. During installation, the installer checks the plugin directory and later uses it after a standard user can replace its contents with a malicious application. Exploitation requires local standard-user access and execution of the plugin installer; the substituted application then runs in the installer's privileged context.

The record

CVE
CVE-2021-34413
Published
Sep 27, 2021
Updated
Aug 4, 2024
Vendor
Zoom Video Communications, Inc.
Product
Zoom Microsoft Outlook Plugin for Windows
Classifications
CWE-367, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 27, 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?

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

  1. Affected versionversion=All versions before 5.3.52553.0918

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Zoom Video Communications, Inc. · Zoom Microsoft Outlook Plugin for Windowsversion=All versions before 5.3.52553.0918

Published CVSS scores

6.0NIST NVDAV:N/AC:M/Au:S/C:P/I:P/A:P
7.5NIST NVDCVSS:3.1/AV:N/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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