CVE-2021-40399Network attack vector

Code execution via freed HtmTableAlt object

Published May 12, 2022 · Updated Apr 15, 2025

Use-after-free in WPS Spreadsheets in WPS Office 11.2.0.10351 allows remote attackers to execute code via a crafted XLS file. The HTML/XML parser frees an HtmTableAlt object during createXmlNodesRef processing, then HtmBoxRefOperator::imitateBoxFlags calls a virtual method through the stale object's overwritten vtable. Exploitation requires a user to open the supplied spreadsheet, and successful heap grooming runs attacker-controlled code in the user's application context.

CVSS severity8.8
High
EPSS probability1.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in WPS Spreadsheets in WPS Office 11.2.0.10351 allows remote attackers to execute code via a crafted XLS file. The HTML/XML parser frees an HtmTableAlt object during createXmlNodesRef processing, then HtmBoxRefOperator::imitateBoxFlags calls a virtual method through the stale object's overwritten vtable. Exploitation requires a user to open the supplied spreadsheet, and successful heap grooming runs attacker-controlled code in the user's application context.

The record

CVE
CVE-2021-40399
Published
May 12, 2022
Updated
Apr 15, 2025
Vendor
Kingsoft Office Software
Product
WPS Office
Classifications
CWE-416, T1204.002, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2025Record 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=11.2.0.10351

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kingsoft Office Software · WPS Officeversion=11.2.0.10351

Published CVSS scores

7.8NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
8.8Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:R/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1204.002Malicious File
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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