CASCACascade Atlas

Evidence dossier

CVE-2021-20090

A path traversal vulnerability in the web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 could allow unauthenticated…

Exploited in the wild (CISA KEV since Nov 3, 2021). NVD reports CVSS 3.1 9.8. EPSS estimates 100.0% exploit likelihood as of Jul 26, 2026.

88.0–89.3Priority evidence range
Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

A path traversal vulnerability in the web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 could allow unauthenticated remote attackers to bypass authentication.

State
PUBLISHED
Published
Apr 29, 2021
Updated
Oct 21, 2025
Evidence coverage
95%

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
    tenable

    Record text: A path traversal vulnerability in the web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 could allow unauthenticated remote attackers to bypass authentication.

    Inspect raw assertion
    Field
    container
    Value
    A path traversal vulnerability in the web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 could allow unauthenticated remote attackers to bypass authentication.
    Original evidence ↗
  4. Source dateFirst observed by CASCA
    CISA KEV

    Exploitation cataloged: Arcadyan Buffalo Firmware Path Traversal Vulnerability

    Inspect raw assertion
    Field
    observed_exploitation
    Value
    Arcadyan Buffalo Firmware Path Traversal Vulnerability
    Original evidence ↗
  5. Source dateFirst observed by CASCA
    FIRST EPSS

    EPSS score: 99.98% probability · 99.98th percentile

    Inspect raw assertion
    Field
    model_probability
    Value
    Probability 0.999800000000; percentile 0.999810000000
    Original evidence ↗
ExploitationCatalog member

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

Exploit likelihood99.98%

FIRST EPSS · score date Jul 26, 2026 · 100th percentile · first observed Jul 27, 2026

SeverityCVSS 9.8

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 ↗
tenableOriginal assertion
Record text

A path traversal vulnerability in the web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 could allow unauthenticated remote attackers to bypass authentication.

Inspect raw assertion
Field
container
Value
A path traversal vulnerability in the web interfaces of Buffalo WSR-2533DHPL2 firmware version <= 1.02 and WSR-2533DHP3 firmware version <= 1.24 could allow unauthenticated remote attackers to bypass authentication.
Source dateSource date omittedFirst observed by CASCAOriginal evidence ↗
CISA KEVOriginal assertion
Exploitation cataloged

Arcadyan Buffalo Firmware Path Traversal Vulnerability

Inspect raw assertion
Field
observed_exploitation
Value
Arcadyan Buffalo Firmware Path Traversal Vulnerability
Source dateFirst observed by CASCAOriginal evidence ↗
FIRST EPSSOriginal assertion
EPSS score

99.98% probability · 99.98th percentile

Inspect raw assertion
Field
model_probability
Value
Probability 0.999800000000; percentile 0.999810000000
Source dateFirst observed by CASCAOriginal evidence ↗

Applicability

Cited product scope

Trace impact →
4Underlying assertions
4Canonical products
2Target assertions
2Constraint assertions

Grouped from 4 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

tenable · source assertedn/aBuffalo WSR-2533DHPL2, Buffalo WSR-2533DHP3Direct source scope
Affected: WSR-2533DHPL2 <=1.02, WSR-2533DHP3 <= 1.24
Source-reported scope

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

Inspect raw assertion[{"status": "affected", "version": "WSR-2533DHPL2 <=1.02, WSR-2533DHP3 <= 1.24"}]
NVD CPE · HARDWAREbuffalowsr-2533dhp3-bkEnvironmental constraint · 1 assertions
Version not applicableCanonical identity product-d83a86a050993dcc79edc8d20adac38915103468687b88d5baa1702ac7416aeeLinked exact
Scope constrained
Inspect raw assertion
  1. cpe:2.3:h:buffalo:wsr-2533dhp3-bk:-:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Environmental constraint
    Configuration
    1 · node/1 · match 0
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    7aa91d93-e2b9-4415-b541-1968f1f39814
NVD CPE · OPERATING SYSTEMbuffalowsr-2533dhp3-bk_firmwareVulnerable target · 1 assertions
Any version (unconstrained) (<= 1.24)Canonical identity product-55460d6d0ca4983295f41b4fe94cac03a88e5ea9a2af5751db5ec67426c0ca05Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:buffalo:wsr-2533dhp3-bk_firmware:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    1 · node/0 · match 0
    Logic
    OR
    Version bounds
    through including 1.24
    Match ID
    63232ec8-b2b8-4867-93db-c0c5147e2730
NVD CPE · HARDWAREbuffalowsr-2533dhpl2-bkEnvironmental constraint · 1 assertions
Version not applicableCanonical identity product-0c8065ae8909922e1e9cbb34d85f52d422f7478fd35eb3075895b30f00a17ed1Linked exact
Scope constrained
Inspect raw assertion
  1. cpe:2.3:h:buffalo:wsr-2533dhpl2-bk:-:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Environmental constraint
    Configuration
    0 · node/1 · match 0
    Logic
    OR
    Version bounds
    No explicit bounds
    Match ID
    1b03fa14-33e3-44d2-8165-197cb446f2d2
NVD CPE · OPERATING SYSTEMbuffalowsr-2533dhpl2-bk_firmwareVulnerable target · 1 assertions
Any version (unconstrained) (<= 1.02)Canonical identity product-f987a7a5b05f69c98dab88993096d0d7e4598ca81cb4efce9e82a5aaa305aab8Linked exact
Scope supported
Inspect raw assertion
  1. cpe:2.3:o:buffalo:wsr-2533dhpl2-bk_firmware:*:*:*:*:*:*:*:*
    Official link
    Linked exact
    Role
    Vulnerable target
    Configuration
    0 · node/0 · match 0
    Logic
    OR
    Version bounds
    through including 1.02
    Match ID
    d861729c-023b-4d73-8c4c-bf7e8b0b7045

Affected-product evidence

Accepted scope and product mapping

2 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-083ec570184b5ac9b4ef0bb3af05fa4630768b4c650e5a0650eb149d2f0d623a · product-55460d6d0ca4983295f41b4fe94cac03a88e5ea9a2af5751db5ec67426c0ca05

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
2c686a83-96ad-4c38-92e2-93247676f6c1
Mapping establishedEvidence supported

vendor-083ec570184b5ac9b4ef0bb3af05fa4630768b4c650e5a0650eb149d2f0d623a · product-f987a7a5b05f69c98dab88993096d0d7e4598ca81cb4efce9e82a5aaa305aab8

Source class
Nvd cpe vulnerable target
Assertions
1
Mapping revision
cpe23-exact-mapping-v1
Observed cutoff
Aug 27, 2026
Retained assertion IDs
635a6bdf-0733-4c51-bda8-fd15e22f1e78
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
7d00a2bc-e892-4aff-a452-91106196170d

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
9.8
CVE Program sourceCVSS 3.1 · role Secondary · priority eligiblevalid_matchCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8
CISA-ADPCVSS 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:H/I:H/A:H

Direct CVE/CNA normalized decisions

9.8Priority eligible

CISA-ADP

CVSS 3.1 · Secondary · Independent enrichment · rank 2

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Validation
Valid match
Recomputed
9.8
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.