CVE-2021-30663

CRITICALNVD 8.89.0▲
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 8.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 5 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: 3%CVSS: 8.8Exploit: cisa kev · ssvc activeExposed: 0

A fix is available — apply it.

An integer overflow was addressed with improved input validation. This issue is fixed in iOS 14.5.1 and iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1. Processing maliciously crafted web content may lead to arbitrary code execution.

CVSS v3
8.8
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
3%
EPSS %ILE
88%
KEV
⚠ Exploited

Published

September 8, 2021

Last Modified

October 23, 2025

Advisory Details (5)

Auto-updated Jun 2, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic

About the security content of Safari 14.1.1 - Apple Support

https://support.apple.com/en-us/HT212534
generic🔴 Active Exploitation

About the security content of tvOS 14.6 - Apple Support

https://support.apple.com/en-us/HT212532
generic🔴 Active Exploitation

About the security content of iOS 12.5.3 - Apple Support

https://support.apple.com/en-us/HT212341
generic🔴 Active Exploitation

About the security content of iOS 14.5.1 and iPadOS 14.5.1 - Apple Support

https://support.apple.com/en-us/HT212336
generic🔴 Active Exploitation

About the security content of macOS Big Sur 11.3.1 - Apple Support

https://support.apple.com/en-us/HT212335

Vendor Advisories for CVE-2021-30663(2)

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

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibwebkit2gtk-4.0-dev (2.32.3-0ubuntu0.21.04.1) @ hirsute2026-09-08ubuntu
redhatwebkitgtk4-0:2.48.3-2.el7_92025-07-07redhat
redhatwebkit2gtk3-0:2.32.3-2.el82021-11-09redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(9 across 5 ecosystems)
Debian:11(2)
PackageVulnerable rangeFixed inDependents
webkit2gtk—2.32.3-1—
wpewebkit—2.32.3-1—
Debian:12(2)
PackageVulnerable rangeFixed inDependents
webkit2gtk—2.32.3-1—
wpewebkit—2.32.3-1—
Debian:13(2)
PackageVulnerable rangeFixed inDependents
webkit2gtk—2.32.3-1—
wpewebkit—2.32.3-1—
Debian:14(2)
PackageVulnerable rangeFixed inDependents
webkit2gtk—2.32.3-1—
wpewebkit—2.32.3-1—
Debian:10(1)
PackageVulnerable rangeFixed inDependents
webkit2gtk2.24.2-1 ... 2.32.2-1 (85 versions)2.32.3-1~deb10u1—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 97× in last 7d / 424× 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 1,395 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(6)

What is CVE-2021-30663?
CVE-2021-30663 is a critical vulnerability published on September 8, 2021. An integer overflow was addressed with improved input validation. This issue is fixed in iOS 14.5.1 and iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1. Processing maliciously crafted web content may lead to arbitrary code execution.
When was CVE-2021-30663 disclosed?
CVE-2021-30663 was first published in the National Vulnerability Database on September 8, 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-2021-30663 actively exploited?
Yes. CISA added CVE-2021-30663 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Apple Multiple Products. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-30663?
CVE-2021-30663 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2021-30663?
CVE-2021-30663 affects Apple Multiple Products. 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-2021-30663?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-30663, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-30663

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