CVE-2021-47971

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-05-16. NVD baseline CVSS 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
7.5EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.5Exploit: Elevated riskExposed services: Not assessed

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

My Notes Safe 5.3 contains a denial of service vulnerability that allows attackers to crash the application by pasting excessively long character strings into note fields. Attackers can generate a payload containing 350000 repeated characters and paste it twice into a new note to trigger an application crash.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
65
EG Risk 65/100CISA SSVC

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
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.3%
EPSS %ILE
19th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

May 16, 2026

Last Modified

May 18, 2026

Advisory Details (2)

Auto-updated May 16, 2026
🔬 Proof of concept available. No fix on record yet.
generic

My Notes Safe 5.3 Denial of Service via Buffer Overflow | Advisories | VulnCheck

https://www.vulncheck.com/advisories/my-notes-safe-denial-of-service-via-buffer-overflow
generic🟡 PoC Available

My Notes Safe 5.3 - Denial of Service (PoC) - iOS dos Exploit

https://www.exploit-db.com/exploits/49954

Vendor Advisories for CVE-2021-47971(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 30× 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 282 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2021-47971?
CVE-2021-47971 is a high vulnerability published on May 16, 2026. My Notes Safe 5.3 contains a denial of service vulnerability that allows attackers to crash the application by pasting excessively long character strings into note fields. Attackers can generate a payload containing 350000 repeated characters and paste it twice into a new note to trigger an…
When was CVE-2021-47971 disclosed?
CVE-2021-47971 was first published on May 16, 2026, with the most recent update on May 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-47971 actively exploited?
CVE-2021-47971 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (19th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-47971?
CVE-2021-47971 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2021-47971?
No fix for CVE-2021-47971 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2021-47971 are linked in the Vendor Advisories panel on this page.

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