How severe is CVE-2021-34359?

CVE-2021-34359 has a CVSS 3.x base score of 6.9, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and user interaction. Impact on confidentiality is high, integrity low, and availability none.

Is CVE-2021-34359 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34359?

CVE-2021-34359 affects Qnap Nas Proxy Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-34359?

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

When was CVE-2021-34359 published?

CVE-2021-34359 was published on 2022-02-25 and last updated on 2026-06-17.

CVE-2021-34359

CVE-2021-34359 is a medium-severity vulnerability in Qnap Nas Proxy Server with a CVSS 3.x base score of 6.9. 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 6.9)
CVSS v2: 3.5
EPSS exploit prediction: 1% (45th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Qnap Nas Proxy Server
Published: 2022-02-25
Last modified: 2026-06-17

Description

A cross-site scripting (XSS) vulnerability has been reported to affect QNAP device running Proxy Server. If exploited, this vulnerability allows remote attackers to inject malicious code. We have already fixed this vulnerability in the following versions of Proxy Server: QTS 4.5.x: Proxy Server 1.4.2 ( 2021/12/30 ) and later

Frequently asked questions

What is CVE-2021-34359?: A cross-site scripting (XSS) vulnerability has been reported to affect QNAP device running Proxy Server. If exploited, this vulnerability allows remote attackers to inject malicious code. We have already fixed this vulnerability in the following versions of Proxy Server: QTS 4.5.x: Proxy Server 1.4.2 ( 2021/12/30 ) and later
How severe is CVE-2021-34359?: CVE-2021-34359 has a CVSS 3.x base score of 6.9, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and user interaction. Impact on confidentiality is high, integrity low, and availability none.
Is CVE-2021-34359 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34359?: CVE-2021-34359 affects Qnap Nas Proxy Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-34359?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-34359 published?: CVE-2021-34359 was published on 2022-02-25 and last updated on 2026-06-17.

References

https://www.qnap.com/en/security-advisory/qsa-22-04

Affected products (1)

cpe:2.3:a:qnap:nas_proxy_server:*:*:*:*:*:*:*:*

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