CVE-2020-7877Network attack vector

Command execution via unchecked OUTERIP parsing

Published Sep 7, 2021 · Updated Aug 4, 2024

Buffer overflow in Mastersoft ZOOK Viewer 2.0.4.6 and Agent 2.0.6.1 allows attackers to execute commands via crafted network data. The ConnectMe command parser copies a crafted OUTERIP value without checking its length, allowing the value to overrun its destination buffer. Exploitation requires low privileges and user interaction, and successful overflow control permits arbitrary command execution.

CVSS severity8.0
High
EPSS probability0.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in Mastersoft ZOOK Viewer 2.0.4.6 and Agent 2.0.6.1 allows attackers to execute commands via crafted network data. The ConnectMe command parser copies a crafted OUTERIP value without checking its length, allowing the value to overrun its destination buffer. Exploitation requires low privileges and user interaction, and successful overflow control permits arbitrary command execution.

The record

CVE
CVE-2020-7877
Published
Sep 7, 2021
Updated
Aug 4, 2024
Vendor
Mastersoft Co., Ltd.
Product
ZOOK Viewer
Classifications
CWE-120, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 7, 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=2.0.4.6 <=2.0.4.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mastersoft Co., Ltd. · ZOOK Viewerversion=2.0.4.6 <=2.0.4.6
Mastersoft Co., Ltd. · ZOOK Agentversion=2.0.6.1 <=2.0.6.1

Published CVSS scores

6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
8.0KrCERT/CCCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
8.8NIST NVDCVSS:3.1/AV:N/AC:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
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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