How severe is CVE-2021-34540?

CVE-2021-34540 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-34540 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34540?

CVE-2021-34540 primarily affects Advantech Webaccess. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-34540?

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

When was CVE-2021-34540 published?

CVE-2021-34540 was published on 2021-06-11 and last updated on 2026-06-17.

CVE-2021-34540

CVE-2021-34540 is a medium-severity vulnerability in Advantech Webaccess with a CVSS 3.x base score of 6.1. 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 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Advantech Webaccess
Published: 2021-06-11
Last modified: 2026-06-17

Description

Advantech WebAccess 8.4.2 and 8.4.4 allows XSS via the username column of the bwRoot.asp page of WADashboard.

Frequently asked questions

What is CVE-2021-34540?: Advantech WebAccess 8.4.2 and 8.4.4 allows XSS via the username column of the bwRoot.asp page of WADashboard.
How severe is CVE-2021-34540?: CVE-2021-34540 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-34540 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34540?: CVE-2021-34540 primarily affects Advantech Webaccess. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-34540?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-34540 published?: CVE-2021-34540 was published on 2021-06-11 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:advantech:webaccess:8.4.2:*:*:*:*:*:*:*
cpe:2.3:a:advantech:webaccess:8.4.4:*:*:*:*:*:*:*

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