CASCACascade Atlas

Evidence dossier

CVE-2020-2506

improper access control vulnerability in Helpdesk

Exploited in the wild (CISA KEV since Mar 25, 2022). NVD reports CVSS 3.1 9.8. Severity assessments differ within at least one CVSS version. EPSS estimates 2.0% exploit likelihood as of Aug 27, 2026.

63.7–71.5Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

The vulnerability have been reported to affect earlier versions of QTS. If exploited, this improper access control vulnerability could allow attackers to compromise the security of the software by gaining privileges, or reading sensitive information. This issue affects: QNAP Systems Inc. Helpdesk versions prior to 3.0.3.

State
PUBLISHED
Published
Feb 3, 2021
Updated
Oct 21, 2025
Evidence coverage
80%

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
    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
    qnap

    Record text: improper access control vulnerability in Helpdesk

    Inspect raw assertion
    Field
    container
    Value
    improper access control vulnerability in Helpdesk
    Original evidence ↗
  4. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: QNAP Helpdesk Improper Access Control Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    QNAP Helpdesk Improper Access Control Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 1.98% probability · 79.09th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.019820000000; percentile 0.790860000000
    Original evidence ↗

Assessments differ

NVD9.8CVSS 3.1 · source date omitted
NVD7.5CVSS 2.0 · source date omitted
security@qnapsecurity.com.tw7.3CVSS 3.1 · source date omitted

Values are shown separately by source and CVSS version.

ExploitationCatalog member

CISA KEV · catalog date Mar 25, 2022 · first observed Jul 19, 2026

Exploit likelihood1.98%

FIRST EPSS · score date Aug 27, 2026 · 79.1th percentile · first observed Aug 27, 2026

SeverityAssessments differ

NVD · CVSS 3.1 · first observed Jul 19, 2026 · values shown separately below

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 assessmentAssessments differ

Eligible assertions materially conflict and remain visible side by side.

Revision
casca-direct-cvss-eligibility-v1
Cutoff
Aug 27, 2026
Resolution
Resolve conflict
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 ↗
qnapOriginal assertion
Record text

improper access control vulnerability in Helpdesk

Inspect raw assertion
Field
container
Value
improper access control vulnerability in Helpdesk
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA KEVOriginal assertion
Exploitation cataloged

QNAP Helpdesk Improper Access Control Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
QNAP Helpdesk Improper Access Control Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

1.98% probability · 79.09th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.019820000000; percentile 0.790860000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
1Underlying assertions
1Canonical products
1Target 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

2 scope groups

qnap · source assertedQNAP Systems Inc.HelpdeskDirect source scope
Affected: unspecified to before 3.0.3 (custom comparison)
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "unspecified", "lessThan": "3.0.3", "versionType": "custom"}]
NVD CPE · APPLICATIONqnaphelpdeskVulnerable target · 1 assertions
Any version (unconstrained) (< 3.0.3)Canonical identity product-94abc3b3e08f6360edb1a860c16670dfa1731039599831202e127c61bd45f968Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:a:qnap:helpdesk:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    through excluding 3.0.3
    Match ID
    a920c2be-51b6-4f9a-8394-e975a5409a12

Affected-product evidence

Accepted scope and product mapping

1 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-37a503905b0a0167877af753ac60ba6a9fd40363b081ec9e83c43aeaec72163a · product-94abc3b3e08f6360edb1a860c16670dfa1731039599831202e127c61bd45f968

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
5a7058a4-900c-4fab-96e6-38356373a405
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
71b78dfe-9474-4002-b90b-9d5f18af74e4

Assessments

CVSS by origin

9.8
NVDCVSS 3.1 · role Primary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5
NVDCVSS 2.0 · role Primary · priority eligiblevalid_matchAV:N/AC:L/Au:N/C:P/I:P/A:P
7.3
security@qnapsecurity.com.twCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
7.3
qnapCVSS 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:L/I:L/A:L

Direct CVE/CNA normalized decisions

7.3Priority eligible

qnap

CVSS 3.1 · Primary · Original assertion · rank 1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Validation
Valid match
Recomputed
7.3
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.