CASCACascade Atlas

Evidence dossier

CVE-2020-9818

An out-of-bounds write issue was addressed with improved bounds checking.

Exploited in the wild (CISA KEV since Nov 3, 2021). NVD reports CVSS 3.1 8.8. EPSS estimates 2.3% exploit likelihood as of Aug 27, 2026.

69.2–71.9Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.

State
PUBLISHED
Published
Jun 9, 2020
Updated
Dec 20, 2025
Evidence coverage
93%

Evidence chronology

What was known when

Download this view's receipt →
  1. Source dateSource date omittedFirst observed by CASCA
    apple

    Record text: An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.

    Inspect raw assertion
    Field
    container
    Value
    An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.
    Original evidence ↗
  2. Source dateSource date omittedFirst observed by CASCA
    CISA-ADP

    Record text: CISA ADP Vulnrichment

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

    Exploitation cataloged: Apple iOS, iPadOS, and watchOS Out-of-Bounds Write Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Apple iOS, iPadOS, and watchOS Out-of-Bounds Write Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 2.29% probability · 81.92th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.022860000000; percentile 0.819190000000
    Original evidence ↗
ExploitationCatalog member

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

Exploit likelihood2.29%

FIRST EPSS · score date Aug 27, 2026 · 81.9th percentile · first observed Aug 27, 2026

SeverityCVSS 8.8

NVD · CVSS 3.1 · first observed Jul 19, 2026 · same-version scores align in this snapshot

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 assessmentEvidence supported

Eligible evidence is present for this bounded claim.

Revision
casca-direct-cvss-eligibility-v1
Cutoff
Aug 27, 2026
Resolution
None
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 out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.

Inspect raw assertion
Field
container
Value
An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.
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

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

Apple iOS, iPadOS, and watchOS Out-of-Bounds Write Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Apple iOS, iPadOS, and watchOS Out-of-Bounds Write Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

2.29% probability · 81.92th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.022860000000; percentile 0.819190000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
4Underlying assertions
3Canonical products
4Target 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

6 scope groups

apple · source assertedAppleiOSDirect source scope
Affected: unspecified to before iOS 13.5 and iPadOS 13.5 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "iOS 13.5 and iPadOS 13.5", "versionType": "custom"}]
apple · source assertedAppleiOS-1Direct source scope
Affected: unspecified to before iOS 12.4.7 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "iOS 12.4.7", "versionType": "custom"}]
apple · source assertedApplewatchOSDirect source scope
Affected: unspecified to before watchOS 6.2.5 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "watchOS 6.2.5", "versionType": "custom"}]
NVD CPE · OPERATING SYSTEMappleipadosVulnerable target · 1 assertions
Any version (unconstrained) (< 13.5)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 0
    Logic
    OR
    Version bounds
    through excluding 13.5
    Match ID
    9145c3cb-429b-4fb8-a0ac-b543e9fff938
NVD CPE · OPERATING SYSTEMappleiphone_osVulnerable target · 2 assertions
Any version (unconstrained) (< 12.4.7); Any version (unconstrained) (>= 13.0, < 13.5)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 1
    Logic
    OR
    Version bounds
    through excluding 12.4.7
    Match ID
    0acd1157-ad87-4487-897f-009fc3204a2a
  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
    from including 13.0; through excluding 13.5
    Match ID
    05af2126-2012-4a6a-bf40-2870d87c85d8
NVD CPE · OPERATING SYSTEMapplewatchosVulnerable target · 1 assertions
Any version (unconstrained) (< 6.2.5)Canonical identity product-1b28e85eba5cb27cd93d563b4ea63a555b916484cee543c65fdbe57d529fc0d1Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:apple:watchos:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 3
    Logic
    OR
    Version bounds
    through excluding 6.2.5
    Match ID
    85301873-69b8-4a21-9efd-f69a5e1abf40

Affected-product evidence

Accepted scope and product mapping

3 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-d6ed6f1e35de2e16a8a10f2ae364dab009bb2afadd609071b20da24d60ce2829 · product-1b28e85eba5cb27cd93d563b4ea63a555b916484cee543c65fdbe57d529fc0d1

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
a2f249df-ac24-4ab2-bf24-346129a2b3c0
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
24e4f902-b7da-473a-8454-9507db06b988788c99f9-b0c1-4fc0-a874-957a31de4b8b
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
d141f66e-ae81-474b-99d6-4f848a070896
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
3
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
3de9a5c7-c945-4ffe-bf26-940b9af5d56645727523-e03f-4798-882f-3bc2f7a5667468d009d6-fc9d-49f0-8065-81a2e1f8654a

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

Direct CVE/CNA normalized decisions

8.8Priority eligible

CISA-ADP

CVSS 3.1 · Secondary · Independent enrichment · rank 2

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Validation
Valid match
Recomputed
8.8
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.