CVE-2021-28798

HIGHNVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.8 under NVD CVSS v3. EPSS exploit probability: 0.9%, top 43% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 8.8Exploit: None knownExposed: 0

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

A relative path traversal vulnerability has been reported to affect QNAP NAS running QTS and QuTS hero. If exploited, this vulnerability allows attackers to modify files that impact system integrity. QNAP have already fixed this vulnerability in the following versions: QTS 4.5.2.1630 Build 20210406 and later QTS 4.3.6.1663 Build 20210504 and later QTS 4.3.3.1624 Build 20210416 and later QuTS hero h4.5.2.1638 Build 20210414 and later QNAP NAS running QTS 4.5.3 are not affected.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: 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
Severity88% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
57%
KEV
Not listed

Published

May 21, 2021

Last Modified

November 21, 2024

References (2)

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 12× 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.

Showing the most recent 100 of 104 total refreshes for this CVE.

  1. 2026-07-26 14:52 UTCEPSS rescore
  2. 2026-07-26 14:52 UTCEPSS rescore
  3. 2026-07-25 14:15 UTCEPSS rescore
  4. 2026-07-24 14:15 UTCEPSS rescore
  5. 2026-07-23 14:16 UTCEPSS rescore
  6. 2026-07-23 01:59 UTCEG score recompute
  7. 2026-07-22 22:46 UTCEG score recompute▲ 1.30
  8. 2026-07-22 14:06 UTCEPSS rescore
  9. 2026-07-22 14:06 UTCEPSS rescore
  10. 2026-07-21 15:22 UTCEPSS rescore
  11. 2026-07-21 15:22 UTCEPSS rescore
  12. 2026-07-20 17:05 UTCEPSS rescore
  13. 2026-07-19 14:28 UTCEPSS rescore
  14. 2026-07-19 02:27 UTCEPSS rescore
  15. 2026-07-19 02:27 UTCEPSS rescore
  16. 2026-07-18 10:02 UTCEPSS rescore
  17. 2026-07-18 10:02 UTCEPSS rescore
  18. 2026-07-16 17:00 UTCEPSS rescore
  19. 2026-07-15 16:55 UTCEPSS rescore
  20. 2026-07-15 16:55 UTCEPSS rescore
  21. 2026-07-15 01:58 UTCEPSS rescore
  22. 2026-07-13 22:27 UTCEPSS rescore
  23. 2026-07-13 22:27 UTCEPSS rescore
  24. 2026-07-13 06:10 UTCEPSS rescore
  25. 2026-07-12 05:44 UTCEPSS rescore
Show 75 more
  1. 2026-07-12 05:44 UTCEPSS rescore
  2. 2026-07-11 08:25 UTCEPSS rescore
  3. 2026-07-11 08:25 UTCEPSS rescore
  4. 2026-07-09 19:07 UTCEPSS rescore
  5. 2026-07-08 15:12 UTCEPSS rescore
  6. 2026-07-07 13:43 UTCEPSS rescore
  7. 2026-07-06 16:25 UTCEPSS rescore
  8. 2026-07-06 16:25 UTCEPSS rescore
  9. 2026-07-06 02:21 UTCEPSS rescore
  10. 2026-07-06 02:21 UTCEPSS rescore
  11. 2026-07-05 02:28 UTCEPSS rescore
  12. 2026-07-04 06:29 UTCEPSS rescore
  13. 2026-07-04 06:29 UTCEPSS rescore
  14. 2026-07-02 16:57 UTCEPSS rescore
  15. 2026-07-01 15:03 UTCEPSS rescore
  16. 2026-06-30 23:20 UTCEPSS rescore
  17. 2026-06-30 23:20 UTCEPSS rescore
  18. 2026-06-29 14:04 UTCEPSS rescore
  19. 2026-06-28 14:05 UTCEPSS rescore
  20. 2026-06-28 04:54 UTCEPSS rescore
  21. 2026-06-28 04:54 UTCEPSS rescore
  22. 2026-06-27 03:06 UTCEPSS rescore
  23. 2026-06-27 03:06 UTCEPSS rescore
  24. 2026-06-25 13:48 UTCEPSS rescore
  25. 2026-06-25 13:48 UTCEPSS rescore
  26. 2026-06-24 14:03 UTCEPSS rescore
  27. 2026-06-24 14:03 UTCEPSS rescore
  28. 2026-06-23 21:31 UTCEPSS rescore
  29. 2026-06-23 21:31 UTCEPSS rescore
  30. 2026-06-22 14:24 UTCEPSS rescore
  31. 2026-06-22 14:24 UTCEPSS rescore
  32. 2026-06-21 14:55 UTCEPSS rescore
  33. 2026-06-21 14:54 UTCEPSS rescore
  34. 2026-06-21 01:58 UTCEPSS rescore
  35. 2026-06-21 01:58 UTCEPSS rescore
  36. 2026-06-19 19:24 UTCEPSS rescore
  37. 2026-06-19 19:24 UTCEPSS rescore
  38. 2026-06-18 17:51 UTCEPSS rescore
  39. 2026-06-18 17:51 UTCEPSS rescore
  40. 2026-06-17 17:51 UTCEPSS rescore
  41. 2026-06-16 17:51 UTCEPSS rescore
  42. 2026-06-15 17:46 UTCEPSS rescore
  43. 2026-06-14 23:15 UTCEPSS rescore
  44. 2026-06-13 22:58 UTCEPSS rescore
  45. 2026-06-13 22:58 UTCEPSS rescore
  46. 2026-06-12 23:10 UTCEPSS rescore
  47. 2026-06-11 13:58 UTCEPSS rescore
  48. 2026-06-10 22:16 UTCEPSS rescore
  49. 2026-06-10 13:20 UTCEPSS rescore
  50. 2026-06-08 14:15 UTCEPSS rescore
  51. 2026-06-07 15:23 UTCEPSS rescore
  52. 2026-06-07 15:23 UTCEPSS rescore
  53. 2026-06-06 13:46 UTCEPSS rescore
  54. 2026-06-06 13:46 UTCEPSS rescore
  55. 2026-06-06 13:46 UTCEPSS rescore
  56. 2026-06-05 22:45 UTCEPSS rescore
  57. 2026-06-05 22:45 UTCEPSS rescore
  58. 2026-06-05 06:09 UTCEPSS rescore
  59. 2026-06-05 06:09 UTCEPSS rescore
  60. 2026-06-04 13:10 UTCEPSS rescore
  61. 2026-06-04 13:10 UTCEPSS rescore
  62. 2026-06-02 20:11 UTCEPSS rescore
  63. 2026-06-02 20:11 UTCEPSS rescore
  64. 2026-06-02 20:11 UTCEPSS rescore
  65. 2026-06-01 13:50 UTCEPSS rescore
  66. 2026-06-01 13:50 UTCEPSS rescore
  67. 2026-05-31 22:29 UTCEPSS rescore
  68. 2026-05-31 22:29 UTCEPSS rescore
  69. 2026-05-31 00:15 UTCEPSS rescore
  70. 2026-05-29 13:42 UTCEPSS rescore
  71. 2026-05-28 13:43 UTCEPSS rescore
  72. 2026-05-28 13:43 UTCEPSS rescore
  73. 2026-05-27 13:39 UTCEPSS rescore
  74. 2026-05-27 13:39 UTCEPSS rescore
  75. 2026-05-26 16:18 UTCEG score recompute

Frequently asked(5)

What is CVE-2021-28798?
CVE-2021-28798 is a high vulnerability published on May 21, 2021. A relative path traversal vulnerability has been reported to affect QNAP NAS running QTS and QuTS hero. If exploited, this vulnerability allows attackers to modify files that impact system integrity. QNAP have already fixed this vulnerability in the following versions: QTS 4.5.2.1630 Build 20210406…
When was CVE-2021-28798 disclosed?
CVE-2021-28798 was first published in the National Vulnerability Database on May 21, 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-2021-28798 actively exploited?
CVE-2021-28798 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 42.8% of all scored CVEs.
What is the CVSS score of CVE-2021-28798?
CVE-2021-28798 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2021-28798?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-28798, 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.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2021-28798

Explore →

Is Your Infrastructure Affected by CVE-2021-28798?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs