CASCACascade Atlas

Evidence dossier

CVE-2026-87491

Out of bounds write in V8 in Google Chrome prior to 153.0.8010.36 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page.

Exploited in the wild (CISA KEV since Sep 9, 2026). CVE Program source reports CVSS 3.1 8.8. EPSS estimates 3.1% exploit likelihood as of Oct 22, 2026.

65.5–69.7Priority evidence range
Evidence through Oct 22, 2026, 6:07 PM UTC

As of Oct 22, 2026

Normalized restatement

Out of bounds write in V8 in Google Chrome prior to 153.0.8010.36 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: Medium)

State
PUBLISHED
Published
Sep 9, 2026
Updated
Sep 21, 2026
Evidence coverage
85%

Evidence chronology

What was known when

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  1. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Google Chromium V8 Out of Bounds Write Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Google Chromium V8 Out of Bounds Write Vulnerability
    Original evidence ↗
  2. Source dateSource date omittedFirst observed by CASCA
    Chrome

    Record text: Out of bounds write in V8 in Google Chrome prior to 153.0.8010.36 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: Medium)

    Inspect raw assertion
    Field
    container
    Value
    Out of bounds write in V8 in Google Chrome prior to 153.0.8010.36 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: Medium)
    Original evidence ↗
  3. 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 ↗
  4. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 3.14% probability · 87.82th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.031420000000; percentile 0.878240000000
    Original evidence ↗
ExploitationCatalog member

CISA KEV · catalog date Sep 9, 2026 · first observed Sep 9, 2026

Exploit likelihood3.14%

FIRST EPSS · score date Oct 22, 2026 · 87.8th percentile · first observed Oct 22, 2026

SeverityCVSS 8.8

CVE Program source · CVSS 3.1 · first observed Sep 26, 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 statusLast verified source snapshot retained

The last verified source boundary remains in force for this claim.

Revision
evidence-policy-v1.1.0
Cutoff
Oct 22, 2026
Resolution
Review source contract
Exploit likelihoodEvidence supported

Eligible evidence is present for this bounded claim.

Revision
evidence-policy-v1.1.0
Cutoff
Oct 22, 2026
Resolution
None
Severity assessmentEvidence supported

Eligible evidence is present for this bounded claim.

Revision
casca-direct-cvss-eligibility-v1
Cutoff
Oct 22, 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
Oct 22, 2026
Resolution
Resolve identity

Source comparison

Who said what

CISA KEVOriginal assertion
Exploitation cataloged

Google Chromium V8 Out of Bounds Write Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Google Chromium V8 Out of Bounds Write Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
ChromeOriginal assertion
Record text

Out of bounds write in V8 in Google Chrome prior to 153.0.8010.36 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: Medium)

Inspect raw assertion
Field
container
Value
Out of bounds write in V8 in Google Chrome prior to 153.0.8010.36 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: Medium)
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 ↗
FIRST EPSSOriginal assertion
EPSS score

3.14% probability · 87.82th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.031420000000; percentile 0.878240000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →

2 scope groups

Chrome · source assertedGoogleChromeDirect source scope
Affected: 153.0.8010.36 to before 153.0.8010.36 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "153.0.8010.36", "lessThan": "153.0.8010.36", "versionType": "custom"}]
NVD · source assertedVendor unspecified by sourceProduct unspecified by sourceDirect source scope
Version bounds not stated
Scope supported
Inspect raw assertioncpe:2.3:a:google:chrome:*:*:*:*:*:*:*:*; end excluding 153.0.8010.36

Affected-product evidence

Accepted scope and product mapping

0 canonical links · 2 source-reported links

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
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Oct 22, 2026
Retained assertion IDs
4c9763d4-b17d-4ada-aeaf-acaafa721757
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
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Oct 22, 2026
Retained assertion IDs
6df54a5d-0547-464f-ab12-f428bb1a42ea

Assessments

CVSS by origin

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.