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 — 4 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%CVSS: 6.1Exploit: cisa kev · ssvc activeExposed: 0

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

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
9.0(high)
EG Risk
81(Attend)
EG Risk 81/100SSVC: Attend

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%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
7%
EPSS %ILE
94%
KEV
⚠ Exploited

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 59× in last 7d / 231× 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 667 total refreshes for this CVE.

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

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 in the National Vulnerability Database 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 patching attention.
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.
Which products are affected by CVE-2021-1879?
CVE-2021-1879 affects Apple iOS, iPadOS, and watchOS. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2021-1879?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-1879, 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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