CVE-2021-43556

Code execution via unchecked TAB data length

Published Dec 28, 2021 · Updated Sep 16, 2024

Stack-based buffer overflow in FATEK Automation WinProladder 3.30_24518 and earlier allows attackers to execute code via a crafted TAB file. The TAB-file parser copies user-supplied data into a stack buffer without first validating its length. A target must open the malicious file or visit a malicious page, after which code runs in the current process context.

CVSS severity7.8
High
EPSS probability2.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in FATEK Automation WinProladder 3.30_24518 and earlier allows attackers to execute code via a crafted TAB file. The TAB-file parser copies user-supplied data into a stack buffer without first validating its length. A target must open the malicious file or visit a malicious page, after which code runs in the current process context.

The record

CVE
CVE-2021-43556
Published
Dec 28, 2021
Updated
Sep 16, 2024
Vendor
FATEK Automation Corporation
Product
WinProladder
Classifications
CWE-121, CWE-787, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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 <=3.30_24518

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

FATEK Automation Corporation · WinProladderversion=All <=3.30_24518

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
7.8ICS-CERTCVSS:3.1/AV:L/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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

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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