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CVE-2021-28797

32
FAUCET Score

CVE-2021-28797 is a critical stack-based buffer overflow vulnerability affecting QNAP NAS devices running Surveillance Station. This flaw allows unauthenticated attackers to execute arbitrary code remotely, posing a severe risk to system integrity and data confidentiality. QNAP has released patches in Surveillance Station versions 5.1.5.4.3 and 5.1.5.3.3 (and later) to address this issue. While no public exploit code or active exploitation has been observed, its high CVSS score of 9.8 (CRITICAL) necessitates immediate patching.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.1.5.3.3CPE matchmatch criteria
cpe:2.3:a:qnap:surveillance_station:*:*:*:*:*:*:*:*
>= 5.1.5.4.0, < 5.1.5.4.3CPE matchmatch criteria
cpe:2.3:a:qnap:surveillance_station:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
5.91%
Probability of exploitation in next 30 days
EPSS Percentile
92.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0591 is in the 87th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

qnap.com / en/security-advisory/qsa-21-07
Vendor Advisory