CVE-2021-1879

CRITICALNVD 6.19.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 6.1 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 3 sources updated this weekExploited in the wild
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 7.1%CVSS: 6.1Exploit: cisa kev · ssvc activeExposed services: Not assessed

A fix is available — apply it.

This issue was addressed by improved management of object lifetimes. This issue is fixed in iOS 12.5.2, iOS 14.4.2 and iPadOS 14.4.2, watchOS 7.3.3. Processing maliciously crafted web content may lead to universal cross site scripting. Apple is aware of a report that this issue may have been actively exploited..

CVSS v3
6.1
EG Score
9.0CRITICALhigh confidence
EG Risk
81
EG Risk 81/100CISA 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
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
7.1%
EPSS %ILE
94th
KEV
⚠ Exploited

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

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation active (CISA Vulnrichment) · Automatable no (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

April 2, 2021

Last Modified

October 23, 2025

Advisory Details (4)

Auto-updated Jun 13, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: cisa.
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1879
generic🔴 Active Exploitation

About the security content of watchOS 7.3.3 - Apple Support

https://support.apple.com/en-us/HT212258
generic🔴 Active Exploitation

About the security content of iOS 12.5.2 - Apple Support

https://support.apple.com/en-us/HT212257
generic🔴 Active Exploitation

About the security content of iOS 14.4.2 and iPadOS 14.4.2 - Apple Support

https://support.apple.com/en-us/HT212256

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 55× in last 7d / 252× 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 1,046 total refreshes for this CVE.

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

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Frequently asked(6)

What is CVE-2021-1879?
CVE-2021-1879 is a critical vulnerability published on April 2, 2021. This issue was addressed by improved management of object lifetimes. This issue is fixed in iOS 12.5.2, iOS 14.4.2 and iPadOS 14.4.2, watchOS 7.3.3. Processing maliciously crafted web content may lead to universal cross site scripting. Apple is aware of a report that this issue may have been…
When was CVE-2021-1879 disclosed?
CVE-2021-1879 was first published on April 2, 2021, with the most recent update on October 23, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-1879 actively exploited?
Yes. CISA added CVE-2021-1879 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Apple iOS, iPadOS, and watchOS. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate attention. A fix is available. Apply it.
What is the CVSS score of CVE-2021-1879?
CVE-2021-1879 has a CVSS v3 base score of 6.1 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0 (CRITICAL).
Which products are affected by CVE-2021-1879?
CVE-2021-1879 affects Apple iOS, iPadOS, and watchOS.
How do I remediate CVE-2021-1879?
A fix for CVE-2021-1879 is available: update to the fixed version the vendor names in its advisory.

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