VulnTideExploited vulnerabilities, by vendor. Data as of 28 Oct 2026.
Known exploitedIn CISA's KEV catalog since 3 November 2021Ransomware use: unknown
Apple Multiple Products

CVE-2021-30661: Apple Multiple Products WebKit Storage Use-After-Free Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, 56 days after the CVE record was published.

How likely is exploitation in the next 30 days?
4.5%

EPSS score, percentile 91.5 of all scored records

How severe?
8.8 High

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA deadline 17 Nov 2021. Apply updates per vendor instructions.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

  • before 14.5
  • before 14.1
  • before 14.5
  • before 7.4
  • before 11.3
  • before 12.5

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

Required action, set by CISA

Apply updates per vendor instructions.

CISA due date for this action: 17 November 2021.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

Affected products and versions

As listed in the CVE record.

Apple iOS and iPadOS
StatusVersions
Affectedbefore 14.5
Apple Safari
StatusVersions
Affectedbefore 14.1
Apple tvOS
StatusVersions
Affectedbefore 14.5
Apple watchOS
StatusVersions
Affectedbefore 7.4
Apple macOS
StatusVersions
Affectedbefore 11.3
Apple macOS
StatusVersions
Affectedbefore 12.5

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Apple iOS, iPadOS, macOS, tvOS, watchOS, and Safari WebKit Storage contain a use-after-free vulnerability that leads to code execution when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

  • CISA added CVE-2021-30661 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Nov 2021.
  • CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
  • The due date CISA sets for the required action is 17 Nov 2021.
  • The CVE record was published on 8 Sep 2021, 56 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 8.8 (High), taken from CISA's enrichment of the record.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 4.5% (percentile 91.5), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

A use after free issue was addressed with improved memory management. This issue is fixed in Safari 14.1, iOS 12.5.3, iOS 14.5 and iPadOS 14.5, watchOS 7.4, tvOS 14.5, macOS Big Sur 11.3. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

DateEvent
8 Sep 2021CVE record published
3 Nov 2021Added to CISA KEV
17 Nov 2021CISA due date for the required action
21 Oct 2025CVE record last updated

References

More exploited Apple vulnerabilities

  • CVE-2026-86950: Apple Multiple Products Out-of-Bounds Write Vulnerability (added 29 Sep 2026)
  • CVE-2026-65400: Apple macOS Improper Authentication Vulnerability (added 18 Aug 2026)
  • CVE-2025-31277: Apple Multiple Products Buffer Overflow Vulnerability (added 20 Mar 2026)
  • CVE-2025-43510: Apple Multiple Products Improper Locking Vulnerability (added 20 Mar 2026)
  • CVE-2025-43520: Apple Multiple Products Classic Buffer Overflow Vulnerability (added 20 Mar 2026)
  • CVE-2021-30952: Apple Multiple Products Integer Overflow or Wraparound Vulnerability (added 5 Mar 2026)