How severe is CVE-2021-42839?

CVE-2021-42839 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-42839 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42839?

CVE-2021-42839 primarily affects Vice Webopac. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-42839?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-42839 published?

CVE-2021-42839 was published on 2021-11-15 and last updated on 2026-06-17.

CVE-2021-42839

CVE-2021-42839 is a high-severity vulnerability in Vice Webopac with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-434.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 9.0
EPSS exploit prediction: 2% (82nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Vice Webopac
Published: 2021-11-15
Last modified: 2026-06-17

Description

Grand Vice info Co. webopac7 file upload function fails to filter special characters. While logging in with general user’s permission, remote attackers can upload malicious script and execute arbitrary code to control the system or interrupt services.

Frequently asked questions

What is CVE-2021-42839?: Grand Vice info Co. webopac7 file upload function fails to filter special characters. While logging in with general user’s permission, remote attackers can upload malicious script and execute arbitrary code to control the system or interrupt services.
How severe is CVE-2021-42839?: CVE-2021-42839 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-42839 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42839?: CVE-2021-42839 primarily affects Vice Webopac. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-42839?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-42839 published?: CVE-2021-42839 was published on 2021-11-15 and last updated on 2026-06-17.

References

https://www.twcert.org.tw/tw/cp-132-5288-9d546-1.html

Affected products (2)

cpe:2.3:a:vice:webopac:1.8.20160701:*:*:*:*:*:*:*
cpe:2.3:a:vice:webopac:7.1.20160701:*:*:*:*:*:*:*

More vulnerabilities in Vice Webopac

CVE-2024-11020 — Critical (CVSS 9.8): Webopac from Grand Vice info has a SQL Injection vulnerability, allowing unauthenticated remote attacks to inject…
CVE-2024-11018 — Critical (CVSS 9.8): Webopac from Grand Vice info does not properly validate uploaded file types, allowing unauthenticated remote attackers…
CVE-2024-11016 — Critical (CVSS 9.8): Webopac from Grand Vice info has a SQL Injection vulnerability, allowing unauthenticated remote attacks to inject…
CVE-2024-11017 — High (CVSS 8.8): Webopac from Grand Vice info does not properly validate uploaded file types, allowing remote attackers with regular…
CVE-2024-11019 — Medium (CVSS 6.1): Webopac from Grand Vice info has a Reflected Cross-site Scripting vulnerability, allowing unauthenticated remote…
CVE-2021-42838 — Medium (CVSS 6.1): Grand Vice info Co. webopac7 book search field parameter does not properly restrict the input of special characters,…

All CVEs affecting Vice Webopac →

Other CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities

CVE-2026-48283 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Unrestricted Upload of File with Dangerous Type…
CVE-2026-48276 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Unrestricted Upload of File with Dangerous Type…
CVE-2026-57700 — Critical (CVSS 10.0): Unrestricted Upload of File with Dangerous Type vulnerability in Daan.Dev OMGF Pro allows Using Malicious Files. This…
CVE-2025-69129 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in WordPress & WooCommerce Scraper Plugin, Import Data from Any Site <= 1.0.7…
CVE-2026-40772 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in GeekyBot <= 1.2.2 versions.
CVE-2026-40412 — Critical (CVSS 10.0): Unrestricted upload of file with dangerous type in Azure Orbital Spatio allows an unauthorized attacker to execute code…

Browse all CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities →