CASCACascade Atlas

Evidence dossier

CVE-2023-6549

Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial of Service and Out-Of-Bounds Memory…

Exploited in the wild (CISA KEV since Jan 17, 2024). NVD reports CVSS 3.1 7.5. EPSS estimates 57.6% exploit likelihood as of Aug 26, 2026.

77.5–80.5Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial of Service and Out-Of-Bounds Memory Read

State
PUBLISHED
Published
Jan 17, 2024
Updated
Oct 21, 2025
Evidence coverage
98%

Evidence chronology

What was known when

Download this view's receipt →
  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
    Citrix

    Record text: Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial of Service and Out-Of-Bounds Memory Read

    Inspect raw assertion
    Field
    container
    Value
    Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial of Service and Out-Of-Bounds Memory Read
    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: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 57.63% probability · 99.01th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.576330000000; percentile 0.990090000000
    Original evidence ↗
ExploitationCatalog member

CISA KEV · catalog date Jan 17, 2024 · first observed Jul 19, 2026

Exploit likelihood57.63%

FIRST EPSS · score date Aug 26, 2026 · 99th percentile · first observed Aug 26, 2026

SeverityCVSS 7.5

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 ↗
CitrixOriginal assertion
Record text

Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial of Service and Out-Of-Bounds Memory Read

Inspect raw assertion
Field
container
Value
Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial of Service and Out-Of-Bounds Memory Read
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

Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

57.63% probability · 99.01th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.576330000000; percentile 0.990090000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
9Underlying assertions
2Canonical products
9Target 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

3 scope groups

Citrix · source assertedCloud Software GroupNetScaler ADCDirect source scope
Affected: 14.1 to before 12.35 (patch comparison)Affected: 13.1 to before 51.15 (patch comparison)Affected: 13.0 to before 92.21 (patch comparison)Affected: 13.1-FIPS to before 37.176 (patch comparison)Affected: 12.1-FIPS to before 55.302 (patch comparison)Affected: 12.1-NDcPP to before 55.302 (patch comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "14.1", "lessThan": "12.35", "versionType": "patch"}, {"status": "affected", "version": "13.1", "lessThan": "51.15", "versionType": "patch"}, {"status": "affected", "version": "13.0", "lessThan": "92.21", "versionType": "patch"}, {"status": "affected", "version": "13.1-FIPS", "lessThan": "37.176", "versionType": "patch"}, {"status": "affected", "version": "12.1-FIPS", "lessThan": "55.302", "versionType": "patch"}, {"status": "affected", "version": "12.1-NDcPP", "lessThan": "55.302", "versionType": "patch"}]
NVD CPE · APPLICATIONcitrixnetscaler_application_delivery_controllerVulnerable target · 6 assertions
Any version (unconstrained) (>= 12.1, < 12.1-55.302); Any version (unconstrained) (>= 13.0, < 13.0-92.21); Any version (unconstrained) (>= 13.1, < 13.1-37.176); Any version (unconstrained) (>= 13.1, < 13.1-51.15); Any version (unconstrained) (>= 14.1, < 14.1-12.35)Canonical identity product-698b699e3cb954f9bb1c9b64d30a2b05877d903ca4042465e866b06d7d56b465Linked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:fips:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    from including 12.1; through excluding 12.1-55.302
    Match ID
    e5672003-8e6b-4316-b5c9-fe436080add1
  2. cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:ndcpp:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 1
    Logic
    OR
    Version bounds
    from including 12.1; through excluding 12.1-55.302
    Match ID
    d1a11abd-4f45-4ba9-b30b-f1d8a612cc15
  3. cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:-:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 2
    Logic
    OR
    Version bounds
    from including 13.0; through excluding 13.0-92.21
    Match ID
    fc0a5aac-62dd-416a-a801-a7a95d5ef73c
  4. cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:fips:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 3
    Logic
    OR
    Version bounds
    from including 13.1; through excluding 13.1-37.176
    Match ID
    8c8a6b95-8338-4ee7-a6ec-7d84aedc4af3
  5. cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:-:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 5
    Logic
    OR
    Version bounds
    from including 14.1; through excluding 14.1-12.35
    Match ID
    62cd82cf-9013-4e54-b175-19b804a351aa
  6. cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:-:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 4
    Logic
    OR
    Version bounds
    from including 13.1; through excluding 13.1-51.15
    Match ID
    3cf77d9d-fc89-493d-b97d-f9699d182f54
NVD CPE · APPLICATIONcitrixnetscaler_gatewayVulnerable target · 3 assertions
Any version (unconstrained) (>= 13.0, < 13.0-92.21); Any version (unconstrained) (>= 13.1, < 13.1-51.15); Any version (unconstrained) (>= 14.1, < 14.1-12.35)Canonical identity product-22e4fbefa2f721b35fa638467110ee91acacd31f29e7473b059c6b09738443c7Linked exact
Scope supported
Inspect raw assertions
  1. cpe:2.3:a:citrix:netscaler_gateway:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 8
    Logic
    OR
    Version bounds
    from including 14.1; through excluding 14.1-12.35
    Match ID
    2836707f-a36f-479e-bfdc-cf55aefc37ee
  2. cpe:2.3:a:citrix:netscaler_gateway:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 7
    Logic
    OR
    Version bounds
    from including 13.1; through excluding 13.1-51.15
    Match ID
    e870c309-d5cd-4181-9deb-4833de2eaeb7
  3. cpe:2.3:a:citrix:netscaler_gateway:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 6
    Logic
    OR
    Version bounds
    from including 13.0; through excluding 13.0-92.21
    Match ID
    68e1f810-abcd-40a7-a8c1-4e8727799c7c

Affected-product evidence

Accepted scope and product mapping

2 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-613dd4bb79ad8759a10407fe624cb651bdb422f3f2780231736f064b614ee756 · product-22e4fbefa2f721b35fa638467110ee91acacd31f29e7473b059c6b09738443c7

Source class
Nvd cpe vulnerable target
Assertions
3
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
142ee28d-b438-4272-9d80-aa3e030212a85c236434-5b48-478b-b156-d3c3334059966a3af85f-c03d-4102-a7f2-6d0035df3a33
Mapping establishedEvidence supported

vendor-613dd4bb79ad8759a10407fe624cb651bdb422f3f2780231736f064b614ee756 · product-698b699e3cb954f9bb1c9b64d30a2b05877d903ca4042465e866b06d7d56b465

Source class
Nvd cpe vulnerable target
Assertions
6
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
1cda3e96-483a-4075-86d4-38b9df9a42f53bba9430-f133-4118-9ca0-8d3b02fc242d71dc6b20-53e5-407f-8f9a-dbcb1645522791a99d64-70a8-4ab5-82ad-ef99b567ad07ba5fe957-77a5-4dc8-81ab-4115ebc2e487e3575ec1-0910-4f6e-825d-1662a981e1b5
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
Aug 27, 2026
Retained assertion IDs
33b3e596-90aa-4d9f-aafd-18477d49daba

Assessments

CVSS by origin

7.5
NVDCVSS 3.1 · role Primary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.2
secure@citrix.comCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
8.2
CitrixCVSS 3.1 · role unknown · display onlyDirect record assessment retained outside normalized eligibilityCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Direct CVE/CNA normalized decisions

8.2Priority eligible

Citrix

CVSS 3.1 · Primary · Original assertion · rank 1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Validation
Valid match
Recomputed
8.2
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.