CASCACascade Atlas

Evidence dossier

CVE-2024-39891

In the Twilio Authy API, accessed by Authy Android before 25.1.0 and Authy iOS before 26.1.0, an unauthenticated endpoint provided access to certain phone-number data, as…

Exploited in the wild (CISA KEV since Jul 23, 2024). NVD reports CVSS 3.1 5.3. EPSS estimates 1.7% exploit likelihood as of Aug 27, 2026.

59.4–62.4Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

In the Twilio Authy API, accessed by Authy Android before 25.1.0 and Authy iOS before 26.1.0, an unauthenticated endpoint provided access to certain phone-number data, as exploited in the wild in June 2024. Specifically, the endpoint accepted a stream of requests containing phone numbers, and responded with information about whether each phone number was registered with Authy. (Authy accounts were not compromised, however.)

State
PUBLISHED
Published
Jul 2, 2024
Updated
Oct 21, 2025
Evidence coverage
91%

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
    mitre

    Record text: In the Twilio Authy API, accessed by Authy Android before 25.1.0 and Authy iOS before 26.1.0, an unauthenticated endpoint provided access to certain phone-number data, as exploited in the wild in June 2024. Specifically, the endpoint accepted a stream of requests containing phone numbers, and responded with information about whether each phone number was registered with Authy. (Authy accounts were not compromised, however.)

    Inspect raw assertion
    Field
    container
    Value
    In the Twilio Authy API, accessed by Authy Android before 25.1.0 and Authy iOS before 26.1.0, an unauthenticated endpoint provided access to certain phone-number data, as exploited in the wild in June 2024. Specifically, the endpoint accepted a stream of requests containing phone numbers, and responded with information about whether each phone number was registered with Authy. (Authy accounts were not compromised, however.)
    Original evidence ↗
  4. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Twilio Authy Information Disclosure Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Twilio Authy Information Disclosure Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 1.67% probability · 75.05th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.016690000000; percentile 0.750480000000
    Original evidence ↗
ExploitationCatalog member

CISA KEV · catalog date Jul 23, 2024 · first observed Jul 19, 2026

Exploit likelihood1.67%

FIRST EPSS · score date Aug 27, 2026 · 75th percentile · first observed Aug 27, 2026

SeverityCVSS 5.3

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 ↗
mitreOriginal assertion
Record text

In the Twilio Authy API, accessed by Authy Android before 25.1.0 and Authy iOS before 26.1.0, an unauthenticated endpoint provided access to certain phone-number data, as exploited in the wild in June 2024. Specifically, the endpoint accepted a stream of requests containing phone numbers, and responded with information about whether each phone number was registered with Authy. (Authy accounts were not compromised, however.)

Inspect raw assertion
Field
container
Value
In the Twilio Authy API, accessed by Authy Android before 25.1.0 and Authy iOS before 26.1.0, an unauthenticated endpoint provided access to certain phone-number data, as exploited in the wild in June 2024. Specifically, the endpoint accepted a stream of requests containing phone numbers, and responded with information about whether each phone number was registered with Authy. (Authy accounts were not compromised, however.)
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA KEVOriginal assertion
Exploitation cataloged

Twilio Authy Information Disclosure Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Twilio Authy Information Disclosure Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

1.67% probability · 75.05th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.016690000000; percentile 0.750480000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
2Underlying assertions
2Canonical products
2Target 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

5 scope groups

mitre · source assertedn/an/aDirect source scope
Affected: n/a
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "n/a"}]
CISA-ADP · source assertedtwilioauthy_2-factor_authenticationDirect source scope
Affected: 0 to before 26.1.0 (custom comparison)Affected: 0 to before 25.1.0 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "0", "lessThan": "26.1.0", "versionType": "custom"}, {"status": "affected", "version": "0", "lessThan": "25.1.0", "versionType": "custom"}]
CISA-ADP · source assertedtwilioauthy_2-factor_authenticationDirect source scope
Affected: 0 to before 26.1.0 (custom comparison)Affected: 0 to before 25.1.0 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "0", "lessThan": "26.1.0", "versionType": "custom"}, {"status": "affected", "version": "0", "lessThan": "25.1.0", "versionType": "custom"}]
NVD CPE · APPLICATIONtwilioauthyVulnerable target · 1 assertions
Any version (unconstrained) (< 26.1.0)Canonical identity product-f0d4905f0f5e8f9638e4c55fa32fc5e5ded9e505778a4dabb90b6fe2a68fe1acLinked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:a:twilio:authy:*:*:*:*:*:iphone_os:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    through excluding 26.1.0
    Match ID
    f645aea3-6acc-4386-aca9-793e66dbf31e
NVD CPE · APPLICATIONtwilioauthy_authenticatorVulnerable target · 1 assertions
Any version (unconstrained) (< 25.1.0)Canonical identity product-b147eff0e884a4bddd2e6afd34e22bbf55541b9e363e726b9e002e2ae12159b4Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:a:twilio:authy_authenticator:*:*:*:*:*:android:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 1
    Logic
    OR
    Version bounds
    through excluding 25.1.0
    Match ID
    07b60ed3-2c9b-46f8-9b6c-1ffb46067d06

Affected-product evidence

Accepted scope and product mapping

2 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-711c64ae48f080b55cc3aecbe0d0d92b6256548411e3b64f399f10f924ad4c3d · product-b147eff0e884a4bddd2e6afd34e22bbf55541b9e363e726b9e002e2ae12159b4

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
22632e6b-6073-4150-a923-8d091e5664d3
Mapping establishedEvidence supported

vendor-711c64ae48f080b55cc3aecbe0d0d92b6256548411e3b64f399f10f924ad4c3d · product-f0d4905f0f5e8f9638e4c55fa32fc5e5ded9e505778a4dabb90b6fe2a68fe1ac

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
c7c1bf94-de9a-45c1-a0b4-6724aa6ccb1d
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
28f99de7-0195-483e-a4cc-68cc7701e2314bb8b29e-a203-4d1a-993b-c4069bd75f78790d38a1-f044-425c-916e-9ce9d56991fe

Assessments

CVSS by origin

5.3
NVDCVSS 3.1 · role Primary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.3
cve@mitre.orgCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.3
mitreCVSS 3.1 · role unknown · display onlyDirect record assessment retained outside normalized eligibilityCVSS:3.1/AC:L/AV:N/A:N/C:L/I:N/PR:N/S:U/UI:N

Direct CVE/CNA normalized decisions

5.3Priority eligible

mitre

CVSS 3.1 · Primary · Original assertion · rank 1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Validation
Valid match
Recomputed
5.3
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.