Evidence dossier

CVE-2025-59287

Windows Server Update Service (WSUS) Remote Code Execution Vulnerability

Exploited in the wild (CISA KEV since Oct 24, 2025). microsoft reports CVSS 3.1 9.8. EPSS estimates 99.9% exploit likelihood as of Aug 8, 2026.

89.8–95.2Priority evidence range

Evidence current through Aug 27, 2026, 6:09 PM UTC

As of Aug 27, 2026

Normalized restatement

Deserialization of untrusted data in Windows Server Update Service allows an unauthorized attacker to execute code over a network.

State: PUBLISHED
Published: Oct 14, 2025
Updated: Feb 26, 2026
Evidence coverage: 90%

Evidence chronology

What was known when

Download this view's receipt →

Source dateSource date omittedFirst observed by CASCAJul 19, 2026
CISA-ADP
Record text: CISA ADP Vulnrichment
Inspect raw assertion
Field
container
Value
CISA ADP Vulnrichment
Original evidence ↗
Source dateSource date omittedFirst observed by CASCAJul 19, 2026
CVE Program
Record text: CVE Program Container
Inspect raw assertion
Field
container
Value
CVE Program Container
Original evidence ↗
Source dateSource date omittedFirst observed by CASCAJul 19, 2026
microsoft
Record text: Windows Server Update Service (WSUS) Remote Code Execution Vulnerability
Inspect raw assertion
Field
container
Value
Windows Server Update Service (WSUS) Remote Code Execution Vulnerability
Original evidence ↗
Source dateJul 16, 2026First observed by CASCAJul 19, 2026
CISA KEV
Exploitation cataloged: Microsoft Windows Server Update Service (WSUS) Deserialization of Untrusted Data Vulnerability
Inspect raw assertion
Field
observed_exploitation
Value
Microsoft Windows Server Update Service (WSUS) Deserialization of Untrusted Data Vulnerability
Original evidence ↗
Source dateAug 8, 2026First observed by CASCAAug 8, 2026
FIRST EPSS
EPSS score: 99.94% probability · 99.97th percentile
Inspect raw assertion
Field
model_probability
Value
Probability 0.999380000000; percentile 0.999700000000
Original evidence ↗

ExploitationCatalog member

CISA KEV · catalog date Oct 24, 2025 · first observed Jul 19, 2026

Exploit likelihood99.94%

FIRST EPSS · score date Aug 8, 2026 · 100th percentile · first observed Aug 8, 2026

SeverityCVSS 9.8

microsoft · 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 CASCAJul 19, 2026Original evidence ↗

CVE ProgramDerivative copy

Record text

CVE Program Container

Inspect raw assertion

Field: container
Value: CVE Program Container

Source dateSource date omittedFirst observed by CASCAJul 19, 2026Original evidence ↗

microsoftOriginal assertion

Record text

Windows Server Update Service (WSUS) Remote Code Execution Vulnerability

Inspect raw assertion

Field: container
Value: Windows Server Update Service (WSUS) Remote Code Execution Vulnerability

Source dateSource date omittedFirst observed by CASCAJul 19, 2026Original evidence ↗

CISA KEVOriginal assertion

Exploitation cataloged

Microsoft Windows Server Update Service (WSUS) Deserialization of Untrusted Data Vulnerability

Inspect raw assertion

Field: observed_exploitation
Value: Microsoft Windows Server Update Service (WSUS) Deserialization of Untrusted Data Vulnerability

Source dateJul 16, 2026First observed by CASCAJul 19, 2026Original evidence ↗

FIRST EPSSOriginal assertion

EPSS score

99.94% probability · 99.97th percentile

Inspect raw assertion

Field: model_probability
Value: Probability 0.999380000000; percentile 0.999700000000

Source dateAug 8, 2026First observed by CASCAAug 8, 2026Original evidence ↗

Applicability

Cited product scope

Trace impact →

7Underlying assertions

6Canonical products

7Target 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

Search scopeRoleOfficial link state

18 scope groups

microsoft · source assertedMicrosoftWindows Server 2012Direct source scope

Affected: 6.2.9200.0 to before 6.2.9200.25728 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.2.9200.0", "lessThan": "6.2.9200.25728", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2012 R2Direct source scope

Affected: 6.3.9600.0 to before 6.3.9600.22826 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.3.9600.0", "lessThan": "6.3.9600.22826", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2012 R2 (Server Core installation)Direct source scope

Affected: 6.3.9600.0 to before 6.3.9600.22826 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.3.9600.0", "lessThan": "6.3.9600.22826", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2012 (Server Core installation)Direct source scope

Affected: 6.2.9200.0 to before 6.2.9200.25728 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "6.2.9200.0", "lessThan": "6.2.9200.25728", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2016Direct source scope

Affected: 10.0.14393.0 to before 10.0.14393.8524 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.14393.0", "lessThan": "10.0.14393.8524", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2016 (Server Core installation)Direct source scope

Affected: 10.0.14393.0 to before 10.0.14393.8524 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.14393.0", "lessThan": "10.0.14393.8524", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2019Direct source scope

Affected: 10.0.17763.0 to before 10.0.17763.7922 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.17763.0", "lessThan": "10.0.17763.7922", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2019 (Server Core installation)Direct source scope

Affected: 10.0.17763.0 to before 10.0.17763.7922 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.17763.0", "lessThan": "10.0.17763.7922", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2022Direct source scope

Affected: 10.0.20348.0 to before 10.0.20348.4297 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.20348.0", "lessThan": "10.0.20348.4297", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2022, 23H2 Edition (Server Core installation)Direct source scope

Affected: 10.0.25398.0 to before 10.0.25398.1916 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.25398.0", "lessThan": "10.0.25398.1916", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2025Direct source scope

Affected: 10.0.26100.0 to before 10.0.26100.6905 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.26100.0", "lessThan": "10.0.26100.6905", "versionType": "custom"}]

microsoft · source assertedMicrosoftWindows Server 2025 (Server Core installation)Direct source scope

Affected: 10.0.26100.0 to before 10.0.26100.6905 (custom comparison)

Source-reported scope

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

Inspect raw assertion

[{"status": "affected", "version": "10.0.26100.0", "lessThan": "10.0.26100.6905", "versionType": "custom"}]

NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2012Vulnerable target · 2 assertions

Version not applicable; Version r2Canonical identity product-5a80416e92fed0cddbb3d4f3840218b448dee11159824ad25a0353da566963feLinked exact

Scope supported

Inspect raw assertions

cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*
Official link
Linked exact
Role
Vulnerable target
Configuration
0 · node/0 · match 0
Logic
OR
Version bounds
No explicit bounds
Match ID
a7df96f8-ba6a-4780-9ca3-f719b3f81074
cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
Official link
Linked exact
Role
Vulnerable target
Configuration
0 · node/0 · match 1
Logic
OR
Version bounds
No explicit bounds
Match ID
db18c4ce-5917-401e-acf7-2747084fd36e

NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2016Vulnerable target · 1 assertions

Any version (unconstrained) (< 10.0.14393.8524)Canonical identity product-02e254d111ce604757a15650ef469f4f8365d6247da82ce3ac2695c3cfc7dc5fLinked exact

Scope supported

Inspect raw assertion

cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
Official link
Linked exact
Role
Vulnerable target
Configuration
0 · node/0 · match 2
Logic
OR
Version bounds
through excluding 10.0.14393.8524
Match ID
7200ef9b-2689-4e9e-be9e-e00836a7d284

NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2019Vulnerable target · 1 assertions

Any version (unconstrained) (< 10.0.17763.7922)Canonical identity product-25a2932c0bbcb648f7e391c8b9d34c734e5085444c03c1c206b9d4c4baa80b25Linked exact

Scope supported

Inspect raw assertion

cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
Official link
Linked exact
Role
Vulnerable target
Configuration
0 · node/0 · match 3
Logic
OR
Version bounds
through excluding 10.0.17763.7922
Match ID
d9ddf9be-8d0b-4027-b3f7-ffd96438e3eb

NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2022Vulnerable target · 1 assertions

Any version (unconstrained) (< 10.0.20348.4297)Canonical identity product-d196d31962e613955a91e33e795c22dcfa7bf25173abebaca616a6350cce9ce1Linked exact

Scope supported

Inspect raw assertion

cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
Official link
Linked exact
Role
Vulnerable target
Configuration
0 · node/0 · match 4
Logic
OR
Version bounds
through excluding 10.0.20348.4297
Match ID
bdac36d7-54a0-456b-b176-17a0b9e63c7a

NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2022_23h2Vulnerable target · 1 assertions

Any version (unconstrained) (< 10.0.25398.1916)Canonical identity product-bc66b50eed682b3633d0f3a2914725d0a72d6d0d5fece14f566d91bc87448c0bLinked exact

Scope supported

Inspect raw assertion

cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*
Official link
Linked exact
Role
Vulnerable target
Configuration
0 · node/0 · match 5
Logic
OR
Version bounds
through excluding 10.0.25398.1916
Match ID
fba85bfd-9802-452e-97b1-6380554ef254

NVD CPE · OPERATING SYSTEMmicrosoftwindows_server_2025Vulnerable target · 1 assertions

Any version (unconstrained) (< 10.0.26100.6905)Canonical identity product-3fe7da0d567cbba9da3f09deea827ccacd90ac3643fc3e1622f75fb001f24443Linked exact

Scope supported

Inspect raw assertion

cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*
Official link
Linked exact
Role
Vulnerable target
Configuration
0 · node/0 · match 6
Logic
OR
Version bounds
through excluding 10.0.26100.6905
Match ID
2e5fff5b-8745-47f6-a0b7-262aa43353bb

Affected-product evidence

Accepted scope and product mapping

6 canonical links · 1 source-reported links

Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-02e254d111ce604757a15650ef469f4f8365d6247da82ce3ac2695c3cfc7dc5f

Source class: Nvd cpe vulnerable target
Assertions: 1
Mapping revision: cpe23-exact-mapping-v1
Observed cutoff: Aug 27, 2026

Retained assertion IDs

7f31802b-0f79-4fef-ae0d-12b9c2d2cc59

Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-25a2932c0bbcb648f7e391c8b9d34c734e5085444c03c1c206b9d4c4baa80b25

Source class: Nvd cpe vulnerable target
Assertions: 1
Mapping revision: cpe23-exact-mapping-v1
Observed cutoff: Aug 27, 2026

Retained assertion IDs

6968b445-e582-4bb5-bbc4-fc29cd34a09b

Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-3fe7da0d567cbba9da3f09deea827ccacd90ac3643fc3e1622f75fb001f24443

Source class: Nvd cpe vulnerable target
Assertions: 1
Mapping revision: cpe23-exact-mapping-v1
Observed cutoff: Aug 27, 2026

Retained assertion IDs

a337fa2c-9a1b-4952-988c-9715b9744320

Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-5a80416e92fed0cddbb3d4f3840218b448dee11159824ad25a0353da566963fe

Source class: Nvd cpe vulnerable target
Assertions: 2
Mapping revision: cpe23-exact-mapping-v1
Observed cutoff: Aug 27, 2026

Retained assertion IDs

338042ae-bd5a-429c-a081-c7e315fbd3c7c0a6c78c-ffa3-4681-98ec-b39591d6e3ef

Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-bc66b50eed682b3633d0f3a2914725d0a72d6d0d5fece14f566d91bc87448c0b

Source class: Nvd cpe vulnerable target
Assertions: 1
Mapping revision: cpe23-exact-mapping-v1
Observed cutoff: Aug 27, 2026

Retained assertion IDs

62828597-690f-4107-ba7d-8ce1ce71037b

Mapping establishedEvidence supported

vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-d196d31962e613955a91e33e795c22dcfa7bf25173abebaca616a6350cce9ce1

Source class: Nvd cpe vulnerable target
Assertions: 1
Mapping revision: cpe23-exact-mapping-v1
Observed cutoff: Aug 27, 2026

Retained assertion IDs

36220761-eb80-4e53-91b1-5a6f3f04c7ec

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: 12
Mapping revision: cpe23-exact-mapping-v1
Observed cutoff: Aug 27, 2026

Retained assertion IDs

0ec432a4-c98a-4428-af1f-84a35cbc7f454393f2ed-d2cc-438e-8015-cab2e9d940095611a6d6-3664-4ca8-90ab-3bd26f9416b25d63d7b7-f93c-4d0d-b50a-eddfd35a560162a4e1bc-4f3d-4b4c-9806-8d3bbe7d0cc17a9acb9c-194c-422c-8376-2fda3427fa157b295bd2-2248-4663-a343-7d95f54e0fc5974e5308-cfb5-4db1-af75-c6a5c849b11599bc93e7-58ba-4dab-bd42-c6655eb1a7a8e3f0194a-9ff4-4420-b052-33e95cbb94c8e5d6e9e8-0017-455a-adc4-afbf66845db6fd817285-0b89-4f4c-9e0f-9086120fcdf7

Assessments

CVSS by origin

9.8

secure@microsoft.comCVSS 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

microsoftCVSS 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/E:P/RL:O/RC:C

Direct CVE/CNA normalized decisions

9.8Priority eligible

microsoft

CVSS 3.1 · Primary · Original assertion · rank 1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C

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.