How severe is CVE-2021-31521?

CVE-2021-31521 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-31521 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31521?

CVE-2021-31521 affects Trendmicro Interscan Web Security Virtual Appliance. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-31521?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-31521 published?

CVE-2021-31521 was published on 2021-06-17 and last updated on 2026-06-17.

CVE-2021-31521

CVE-2021-31521 is a medium-severity vulnerability in Trendmicro Interscan Web Security Virtual Appliance with a CVSS 3.x base score of 5.4. 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-79.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
CVSS v2: 3.5
EPSS exploit prediction: 1% (69th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Trendmicro Interscan Web Security Virtual Appliance
Published: 2021-06-17
Last modified: 2026-06-17

Description

Trend Micro InterScan Web Security Virtual Appliance version 6.5 was found to have a reflected cross-site scripting (XSS) vulnerability in the product's Captive Portal.

Frequently asked questions

What is CVE-2021-31521?: Trend Micro InterScan Web Security Virtual Appliance version 6.5 was found to have a reflected cross-site scripting (XSS) vulnerability in the product's Captive Portal.
How severe is CVE-2021-31521?: CVE-2021-31521 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-31521 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31521?: CVE-2021-31521 affects Trendmicro Interscan Web Security Virtual Appliance. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-31521?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-31521 published?: CVE-2021-31521 was published on 2021-06-17 and last updated on 2026-06-17.

References

https://success.trendmicro.com/solution/000286452

Affected products (1)

cpe:2.3:a:trendmicro:interscan_web_security_virtual_appliance:6.5:sp2:*:*:*:*:*:*

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