How severe is CVE-2021-34345?

CVE-2021-34345 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-34345 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34345?

CVE-2021-34345 primarily affects Qnap Ej1600 Firmware. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-34345?

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

When was CVE-2021-34345 published?

CVE-2021-34345 was published on 2021-09-10 and last updated on 2026-06-17.

CVE-2021-34345

CVE-2021-34345 is a critical-severity vulnerability in Qnap Ej1600 Firmware with a CVSS 3.x base score of 9.8. 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-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Qnap Ej1600 Firmware
Published: 2021-09-10
Last modified: 2026-06-17

Description

A stack buffer overflow vulnerability has been reported to affect QNAP device running NVR Storage Expansion. If exploited, this vulnerability allows attackers to execute arbitrary code. We have already fixed this vulnerability in the following versions of NVR Storage Expansion: NVR Storage Expansion 1.0.6 ( 2021/08/03 ) and later

Frequently asked questions

What is CVE-2021-34345?: A stack buffer overflow vulnerability has been reported to affect QNAP device running NVR Storage Expansion. If exploited, this vulnerability allows attackers to execute arbitrary code. We have already fixed this vulnerability in the following versions of NVR Storage Expansion: NVR Storage Expansion 1.0.6 ( 2021/08/03 ) and later
How severe is CVE-2021-34345?: CVE-2021-34345 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-34345 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34345?: CVE-2021-34345 primarily affects Qnap Ej1600 Firmware. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-34345?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-34345 published?: CVE-2021-34345 was published on 2021-09-10 and last updated on 2026-06-17.

References

https://www.qnap.com/en/security-advisory/qsa-21-36

Affected products (14)

cpe:2.3:o:qnap:ej1600_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tl-r1620sdc_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tl-r1620sep-rp_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tl-r1220sep-rp_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tl-d1600s_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tl-d800s_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tl-d400s_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tl-r1200s-rp_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tl-r400s_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tl-r1200c-rp_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tl-d800c_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tr-004_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tr-002_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:qnap:tr-004u_firmware:*:*:*:*:*:*:*:*

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