CVE-2021-26618

Code execution via arbitrary file creation

Published Feb 18, 2022 · Updated Aug 3, 2024

Improper input validation in ToWord in TmaxSoft ToOffice 3.15.5 and earlier allows attackers to execute code through a crafted DOCX file. ToWord extracts ZIP content from the DOCX and creates files without validating their destination, allowing a malicious file to be written into the Windows Startup folder. Execution requires a user to open the disguised document and then restart Windows, after which the planted file runs in that user context.

CVSS severity7.1
High
EPSS probability1.00%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in ToWord in TmaxSoft ToOffice 3.15.5 and earlier allows attackers to execute code through a crafted DOCX file. ToWord extracts ZIP content from the DOCX and creates files without validating their destination, allowing a malicious file to be written into the Windows Startup folder. Execution requires a user to open the disguised document and then restart Windows, after which the planted file runs in that user context.

The record

CVE
CVE-2021-26618
Published
Feb 18, 2022
Updated
Aug 3, 2024
Vendor
TmaxSoft Co., Ltd.
Product
ToOffice
Classifications
CWE-20, T1204.002, T1547.001
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 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 <=3.15.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

TmaxSoft Co., Ltd. · ToOfficeversion=unspecified <=3.15.5

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
7.1KrCERT/CCCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1204.002Malicious File
T1547.001Registry Run Keys / Startup Folder

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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