CVE-2021-42839Network attack vector

Code execution via special-character upload bypass

Published Nov 15, 2021 · Updated Sep 17, 2024

Unrestricted file upload in Grand Vice info Co. WebOPAC7 1.8.20160701 and 7.1.20160701 allows remote authenticated users to execute code. The upload page URL does not filter special characters, allowing crafted input to bypass file-type checks and place an executable script. General-user credentials are required; executing the uploaded script grants control of the server and can interrupt its service.

CVSS severity8.8
High
EPSS probability2.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unrestricted file upload in Grand Vice info Co. WebOPAC7 1.8.20160701 and 7.1.20160701 allows remote authenticated users to execute code. The upload page URL does not filter special characters, allowing crafted input to bypass file-type checks and place an executable script. General-user credentials are required; executing the uploaded script grants control of the server and can interrupt its service.

The record

CVE
CVE-2021-42839
Published
Nov 15, 2021
Updated
Sep 17, 2024
Vendor
Grand Vice info Co.
Product
WebOPAC7
Classifications
CWE-434, T1505.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=1.8.20160701
  2. Affected versionversion=7.1.20160701

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Grand Vice info Co. · WebOPAC7version=1.8.20160701; version=7.1.20160701

Published CVSS scores

8.8TWCERT/CCCVSS: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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1505.003Server Software Component: Web Shell

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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