CASCACascade Atlas

Evidence dossier

CVE-2019-17026

Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion.

Exploited in the wild (CISA KEV since Nov 3, 2021). NVD reports CVSS 3.1 8.8. EPSS estimates 46.6% exploit likelihood as of Aug 26, 2026.

80.5–82.8Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.

State
PUBLISHED
Published
Mar 2, 2020
Updated
Oct 21, 2025
Evidence coverage
93%

Evidence chronology

What was known when

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  1. 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 ↗
  2. 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 ↗
  3. Source dateSource date omittedFirst observed by CASCA
    mozilla

    Record text: Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.

    Inspect raw assertion
    Field
    container
    Value
    Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.
    Original evidence ↗
  4. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Mozilla Firefox And Thunderbird Type Confusion Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Mozilla Firefox And Thunderbird Type Confusion Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 46.59% probability · 98.73th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.465890000000; percentile 0.987300000000
    Original evidence ↗
ExploitationCatalog member

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

Exploit likelihood46.59%

FIRST EPSS · score date Aug 26, 2026 · 98.7th percentile · first observed Aug 26, 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

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 ↗
mozillaOriginal assertion
Record text

Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.

Inspect raw assertion
Field
container
Value
Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA KEVOriginal assertion
Exploitation cataloged

Mozilla Firefox And Thunderbird Type Confusion Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Mozilla Firefox And Thunderbird Type Confusion Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

46.59% probability · 98.73th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.465890000000; percentile 0.987300000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
4Underlying assertions
3Canonical products
4Target assertions
0Constraint assertions

Grouped from 2 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

mozilla · source assertedMozillaFirefoxDirect source scope
Affected: unspecified to before 72.0.1 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "72.0.1", "versionType": "custom"}]
mozilla · source assertedMozillaFirefox ESRDirect source scope
Affected: unspecified to before 68.4.1 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "68.4.1", "versionType": "custom"}]
mozilla · source assertedMozillaThunderbirdDirect source scope
Affected: unspecified to before 68.4.1 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "68.4.1", "versionType": "custom"}]
NVD CPE · OPERATING SYSTEMcanonicalubuntu_linuxVulnerable target · 1 assertions
Version 16.04Canonical identity product-a18840e4673d48e569064752e9575849e99b3f173c63d7c965c4c193bcaebef2Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    1 · node/0 · match 0
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    7a5301bf-1402-4be0-a0f8-69fbe79bc6d6
NVD CPE · APPLICATIONmozillafirefoxVulnerable target · 2 assertions
Any version (unconstrained) (< 68.4.1); Any version (unconstrained) (< 72.0.1)Canonical identity product-07fd419647bc4be85f7cd99fb6db991c405f59f4526c86f98007cccadd88fb6bLinked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 1
    Logic
    OR
    Version bounds
    through excluding 72.0.1
    Match ID
    0fc8a283-5e66-4ead-a36a-0b0247b6ee50
  2. cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    through excluding 68.4.1
    Match ID
    a1ec26e6-7cbe-4386-9e43-961a21639526
NVD CPE · APPLICATIONmozillathunderbirdVulnerable target · 1 assertions
Any version (unconstrained) (< 68.4.1)Canonical identity product-148c720470a65e23ffba2cd2146b70004a125bb02def92b1d58b670632c22fffLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 2
    Logic
    OR
    Version bounds
    through excluding 68.4.1
    Match ID
    bd9c9431-2f4c-4c13-848b-0e0c6a811f47

Affected-product evidence

Accepted scope and product mapping

3 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-a8002e9a4c58b83fa97f47fe42903a60facd8770768e9b325e288d873b8b8255 · product-07fd419647bc4be85f7cd99fb6db991c405f59f4526c86f98007cccadd88fb6b

Source class
Nvd cpe vulnerable target
Assertions
2
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
8557a67d-da4c-43c4-9ae3-275cdea5390ea996ca44-2665-4c15-9362-b1b68447238a
Mapping establishedEvidence supported

vendor-a8002e9a4c58b83fa97f47fe42903a60facd8770768e9b325e288d873b8b8255 · product-148c720470a65e23ffba2cd2146b70004a125bb02def92b1d58b670632c22fff

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
1e00e7e8-0eb0-466d-a079-5558572a9ba4
Mapping establishedEvidence supported

vendor-c57a6167e95991f72f9616ac32b40463ac13c5f4929fcce3efc058b09a445b54 · product-a18840e4673d48e569064752e9575849e99b3f173c63d7c965c4c193bcaebef2

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
09d9d903-0470-4ebd-a4a0-73cb6d410320
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
42490156-6382-4944-bb68-69795747d1ad8f3b44a9-0331-47c5-8b46-40fba689cf58b1a9197c-4aa1-4e1c-b22a-67d7c41eda5c

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.