CASCACascade Atlas

Evidence dossier

CVE-2021-30663

An integer overflow was addressed with improved input validation.

Exploited in the wild (CISA KEV since Nov 3, 2021). NVD reports CVSS 3.1 8.8. Severity assessments differ within at least one CVSS version. EPSS estimates 3.5% exploit likelihood as of Aug 27, 2026.

68.3–74.1Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

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.

State
PUBLISHED
Published
Sep 8, 2021
Updated
Oct 21, 2025
Evidence coverage
80%

Evidence chronology

What was known when

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  1. Source dateSource date omittedFirst observed by CASCA
    apple

    Record text: 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.

    Inspect raw assertion
    Field
    container
    Value
    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.
    Original evidence ↗
  2. Source dateSource date omittedFirst observed by CASCA
    CISA-ADP

    Record text: CISA ADP Vulnrichment

    Inspect raw assertion
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    container
    Value
    CISA ADP Vulnrichment
    Original evidence ↗
  3. Source dateSource date omittedFirst observed by CASCA
    CVE Program

    Record text: CVE Program Container

    Inspect raw assertion
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    container
    Value
    CVE Program Container
    Original evidence ↗
  4. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Apple Multiple Products WebKit Integer Overflow Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Apple Multiple Products WebKit Integer Overflow Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 3.49% probability · 88.28th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.034930000000; percentile 0.882800000000
    Original evidence ↗

Assessments differ

NVD8.8CVSS 3.1 · source date omitted
NVD6.8CVSS 2.0 · source date omitted
CVE Program source7.8CVSS 3.1 · source date omitted

Values are shown separately by source and CVSS version.

ExploitationCatalog member

CISA KEV · catalog date Nov 3, 2021 · first observed Jul 19, 2026

Exploit likelihood3.49%

FIRST EPSS · score date Aug 27, 2026 · 88.3th percentile · first observed Aug 27, 2026

SeverityAssessments differ

NVD · CVSS 3.1 · first observed Jul 19, 2026 · values shown separately below

Evidence detail

Source limits and decisions

Why each evidence state has this value

casca-unknown-reasons-v1
Exploitation statusEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Aug 27, 2026
Resolution
None
Exploit likelihoodEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Aug 27, 2026
Resolution
None
Severity assessmentAssessments differ

Eligible assertions materially conflict and remain visible side by side.

Revision
casca-direct-cvss-eligibility-v1
Cutoff
Aug 27, 2026
Resolution
Resolve conflict
Affected productsSource-reported scope

The cited source assertion is retained while canonical product linkage remains open.

Revision
casca-factor-d-obligations-v1
Cutoff
Aug 27, 2026
Resolution
Resolve identity

Source comparison

Who said what

appleOriginal assertion
Record text

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.

Inspect raw assertion
Field
container
Value
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.
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA-ADPIndependent enrichment
Record text

CISA ADP Vulnrichment

Inspect raw assertion
Field
container
Value
CISA ADP Vulnrichment
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CVE ProgramDerivative copy
Record text

CVE Program Container

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Field
container
Value
CVE Program Container
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA KEVOriginal assertion
Exploitation cataloged

Apple Multiple Products WebKit Integer Overflow Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Apple Multiple Products WebKit Integer Overflow Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

3.49% probability · 88.28th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.034930000000; percentile 0.882800000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
6Underlying assertions
5Canonical products
6Target assertions
0Constraint assertions

Grouped from 1 configuration nodes in this exact snapshot. Visual grouping is navigational; asset exposure and root cause require cited evidence.

Identity source boundaries
  • Cpe dictionary1,775,266 records · observed through 2026-07-21T06:45:29.809Z27d65b0f-b718-4b4f-bb79-c47c68d09dfa
  • Cpe match643,502 records · observed through 2026-07-21T08:13:17.697Z955dae73-7302-438b-aee1-058d7cc5d48e

10 scope groups

apple · source assertedApplemacOSDirect source scope
Affected: unspecified to before 11.3 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "11.3", "versionType": "custom"}]
apple · source assertedApplemacOSDirect source scope
Affected: unspecified to before 14.5 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "14.5", "versionType": "custom"}]
apple · source assertedApplemacOSDirect source scope
Affected: unspecified to before 12.5 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "12.5", "versionType": "custom"}]
apple · source assertedApplemacOSDirect source scope
Affected: unspecified to before 14.6 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "14.6", "versionType": "custom"}]
apple · source assertedApplemacOSDirect source scope
Affected: unspecified to before 14.1 (custom comparison)
Source-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "14.1", "versionType": "custom"}]
NVD CPE · OPERATING SYSTEMappleipadosVulnerable target · 1 assertions
Any version (unconstrained) (>= 14.0, < 14.5.1)Canonical identity product-8e7094ac066248cd4828b6ec8e3a96d010ed1c68f6083af46638775d737da0adLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:apple:ipados:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 1
    Logic
    OR
    Version bounds
    from including 14.0; through excluding 14.5.1
    Match ID
    35bd9c02-08c2-45a2-bc2c-a19111c293f3
NVD CPE · OPERATING SYSTEMappleiphone_osVulnerable target · 2 assertions
Any version (unconstrained) (< 12.5.3); Any version (unconstrained) (>= 14.0, < 14.5.1)Canonical identity product-665d7155d02581979844685e7fca6c2680af997f9200af455887b1c71c483272Linked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 3
    Logic
    OR
    Version bounds
    from including 14.0; through excluding 14.5.1
    Match ID
    ebbd83ad-8615-422b-ae3e-39d4ab86d8fc
  2. cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 2
    Logic
    OR
    Version bounds
    through excluding 12.5.3
    Match ID
    443bf1fd-ec67-437d-a9ca-eeb3ef25b701
NVD CPE · OPERATING SYSTEMapplemacosVulnerable target · 1 assertions
Any version (unconstrained) (>= 11.0, < 11.3.1)Canonical identity product-d6f53ba981bb58ea2b0d24855b8ff4a18555e3a17a9dce0d38460a69537bbc63Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 4
    Logic
    OR
    Version bounds
    from including 11.0; through excluding 11.3.1
    Match ID
    14b2f397-655e-44c5-b9a3-8c4435675f42
NVD CPE · APPLICATIONapplesafariVulnerable target · 1 assertions
Any version (unconstrained) (< 14.1.1)Canonical identity product-3c7772db507b09c802755f0f7a9c9fce988300ebb3425947843e4ccbcfe8ffedLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:a:apple:safari:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    through excluding 14.1.1
    Match ID
    ffda8ce0-8f2c-4fa7-91f8-a720f56ebc5d
NVD CPE · OPERATING SYSTEMappletvosVulnerable target · 1 assertions
Any version (unconstrained) (< 14.6)Canonical identity product-e5ea88731ef28ba75a5b40a72b650d8199d1f49ce8c4cd688de7cdb41dc8b9fbLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:apple:tvos:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 5
    Logic
    OR
    Version bounds
    through excluding 14.6
    Match ID
    9076d8c8-70cd-4de5-8bae-8ca6a5beddb3

Affected-product evidence

Accepted scope and product mapping

5 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-d6ed6f1e35de2e16a8a10f2ae364dab009bb2afadd609071b20da24d60ce2829 · product-3c7772db507b09c802755f0f7a9c9fce988300ebb3425947843e4ccbcfe8ffed

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
193f7a8f-3f70-48ad-8533-499b1aa11ff3
Mapping establishedEvidence supported

vendor-d6ed6f1e35de2e16a8a10f2ae364dab009bb2afadd609071b20da24d60ce2829 · product-665d7155d02581979844685e7fca6c2680af997f9200af455887b1c71c483272

Source class
Nvd cpe vulnerable target
Assertions
2
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
3427394f-7989-41e3-a57e-41bd365eef5ed009c79e-96a7-45eb-bb74-cfc2620feb57
Mapping establishedEvidence supported

vendor-d6ed6f1e35de2e16a8a10f2ae364dab009bb2afadd609071b20da24d60ce2829 · product-8e7094ac066248cd4828b6ec8e3a96d010ed1c68f6083af46638775d737da0ad

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
bab8a129-9297-4cd8-afab-8800ce2ccd1d
Mapping establishedEvidence supported

vendor-d6ed6f1e35de2e16a8a10f2ae364dab009bb2afadd609071b20da24d60ce2829 · product-d6f53ba981bb58ea2b0d24855b8ff4a18555e3a17a9dce0d38460a69537bbc63

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
83e2e2c7-58c3-4a6a-a163-f56451bc7526
Mapping establishedEvidence supported

vendor-d6ed6f1e35de2e16a8a10f2ae364dab009bb2afadd609071b20da24d60ce2829 · product-e5ea88731ef28ba75a5b40a72b650d8199d1f49ce8c4cd688de7cdb41dc8b9fb

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
8cef9e03-387f-4bae-9833-ff65605ef1f4
Source-reported scopeSource-reported scope

Canonical linkage remains open; the cited source assertion is retained below.

Vendor specified only by source · Product specified only by source

Source class
Direct cve affected
Assertions
5
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
25f456f8-6bc5-4b77-b3b0-bb28cc0d4d1749218896-7cb3-4ac5-976d-256fe0845a0f55a9d8df-2c85-4938-a65f-ea0436ed23a8b8e52170-2e7e-4536-a57d-e0f48da469d3f738020e-9bec-4f24-bc01-5e697c60d949

Assessments

CVSS by origin

8.8
NVDCVSS 3.1 · role Primary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8
NVDCVSS 2.0 · role Primary · priority eligiblevalid_matchAV:N/AC:M/Au:N/C:P/I:P/A:P
7.8
CVE Program sourceCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
7.8
CISA-ADPCVSS 3.1 · role unknown · display onlyDirect record assessment retained outside normalized eligibilityCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Direct CVE/CNA normalized decisions

7.8Priority eligible

CISA-ADP

CVSS 3.1 · Secondary · Independent enrichment · rank 2

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Validation
Valid match
Recomputed
7.8
Decision reason
Evidence supported
Policy
casca-direct-cvss-eligibility-v1

Assessments are retained side by side under closed precedence. Cascade never averages CVSS.

Evidence boundaries

  • KEV membership is authoritative for the catalog, not proof of exposure in any environment.
  • EPSS is a dated model probability and not an individual-environment prediction.
  • Affected or fixed status applies only to the exact cited product and version scope; remaining scope stays source-scoped.
  • NVD-carried upstream facts remain derivative; independent corroboration requires a separately authored source.
  • Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
  • NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.
  • OSV aggregation and OSV-converted NVD material are not independent corroboration.
  • Red Hat facts are vendor assertions for the exact supplied products.
  • Nonmembership and not-yet-observed states are not proof of safety.