CVE-2021-34345 | Stack Based Overflow Vulnerability in NVR Storage Expansion

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

Published: 2021-09-10 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-34345 is rated Moderate Risk (64.6/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 1.58%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-34345

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-07-04 1.53% 1.58% +0.05%
2 2026-06-15 1.21% 1.53% +0.31%
3 2025-03-30 — 1.21% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-34345

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2021-34345

Affected software / configurations for CVE-2021-34345

Vendor Product Version Raw CPE
qnap ej1600_firmware < 1.0.6 cpe:2.3:o:qnap:ej1600_firmware:*:*:*:*:*:*:*:*
qnap tl-r1620sdc_firmware < 1.0.6 cpe:2.3:o:qnap:tl-r1620sdc_firmware:*:*:*:*:*:*:*:*
qnap tl-r1620sep-rp_firmware < 1.0.6 cpe:2.3:o:qnap:tl-r1620sep-rp_firmware:*:*:*:*:*:*:*:*
qnap tl-r1220sep-rp_firmware < 1.0.6 cpe:2.3:o:qnap:tl-r1220sep-rp_firmware:*:*:*:*:*:*:*:*
qnap tl-d1600s_firmware < 1.0.6 cpe:2.3:o:qnap:tl-d1600s_firmware:*:*:*:*:*:*:*:*
qnap tl-d800s_firmware < 1.0.6 cpe:2.3:o:qnap:tl-d800s_firmware:*:*:*:*:*:*:*:*
qnap tl-d400s_firmware < 1.0.6 cpe:2.3:o:qnap:tl-d400s_firmware:*:*:*:*:*:*:*:*
qnap tl-r1200s-rp_firmware < 1.0.6 cpe:2.3:o:qnap:tl-r1200s-rp_firmware:*:*:*:*:*:*:*:*
qnap tl-r400s_firmware < 1.0.6 cpe:2.3:o:qnap:tl-r400s_firmware:*:*:*:*:*:*:*:*
qnap tl-r1200c-rp_firmware < 1.0.6 cpe:2.3:o:qnap:tl-r1200c-rp_firmware:*:*:*:*:*:*:*:*
qnap tl-d800c_firmware < 1.0.6 cpe:2.3:o:qnap:tl-d800c_firmware:*:*:*:*:*:*:*:*
qnap tr-004_firmware < 1.0.6 cpe:2.3:o:qnap:tr-004_firmware:*:*:*:*:*:*:*:*
qnap tr-002_firmware < 1.0.6 cpe:2.3:o:qnap:tr-002_firmware:*:*:*:*:*:*:*:*
qnap tr-004u_firmware < 1.0.6 cpe:2.3:o:qnap:tr-004u_firmware:*:*:*:*:*:*:*:*

References for CVE-2021-34345

cvelogic Threat Intelligence