CVE-2021-28797

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 5.9%, top 8% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 6%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

A stack-based buffer overflow vulnerability has been reported to affect QNAP NAS devices running Surveillance Station. If exploited, this vulnerability allows attackers to execute arbitrary code. QNAP have already fixed this vulnerability in the following versions: Surveillance Station 5.1.5.4.3 (and later) for ARM CPU NAS (64bit OS) and x86 CPU NAS (64bit OS) Surveillance Station 5.1.5.3.3 (and later) for ARM CPU NAS (32bit OS) and x86 CPU NAS (32bit OS)

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
51(Track)
EG Risk 51/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation6% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
92.5%
KEV
Not listed

Published

April 14, 2021

Last Modified

November 21, 2024

Advisory Details (1)

Auto-updated Jun 21, 2026
No patch confirmed yet.
generic

Stack Buffer Overflow in Surveillance Station - Security Advisory | QNAP

https://www.qnap.com/en/security-advisory/qsa-21-07

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 46× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 14:16 UTCEPSS rescore
  2. 2026-07-23 01:59 UTCEG score recompute
  3. 2026-07-22 22:46 UTCEG score recompute
  4. 2026-07-22 14:06 UTCEPSS rescore
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  1. 2026-07-07 13:43 UTCEPSS rescore
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  40. 2026-06-10 22:16 UTCEPSS rescore
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  45. 2026-06-06 13:46 UTCEPSS rescore
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  67. 2026-05-26 18:19 UTCEG score recompute
  68. 2026-05-26 18:19 UTCGHSA enrichment
  69. 2026-05-26 13:42 UTCEPSS rescore
  70. 2026-05-26 07:17 UTCEPSS rescore
  71. 2026-05-26 07:17 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2021-28797?
CVE-2021-28797 is a critical vulnerability published on April 14, 2021. A stack-based buffer overflow vulnerability has been reported to affect QNAP NAS devices running Surveillance Station. If exploited, this vulnerability allows attackers to execute arbitrary code. QNAP have already fixed this vulnerability in the following versions: Surveillance Station 5.1.5.4.3…
When was CVE-2021-28797 disclosed?
CVE-2021-28797 was first published in the National Vulnerability Database on April 14, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-28797 actively exploited?
CVE-2021-28797 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 92.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-28797?
CVE-2021-28797 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-28797?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-28797, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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