CISA KEV · catalog date Nov 3, 2021 · first observed Jul 19, 2026
Evidence dossier
CVE-2021-34527
Windows Print Spooler Remote Code Execution Vulnerability
Exploited in the wild (CISA KEV since Nov 3, 2021). microsoft reports CVSS 3.1 8.8. EPSS estimates 99.8% exploit likelihood as of Aug 9, 2026.
As of Aug 27, 2026
Normalized restatement
<p>A remote code execution vulnerability exists when the Windows Print Spooler service improperly performs privileged file operations. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.</p> <p>UPDATE July 7, 2021: The security update for Windows Server 2012, Windows Server 2016 and Windows 10, Version 1607 have been released. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability.</p> <p>In addition to installing the updates, in order to secure your system, you must confirm that the following registry settings are set to 0 (zero) or are not defined (<strong>Note</strong>: These registry keys do not exist by default, and therefore are already at the secure setting.), also that your Group Policy setting are correct (see FAQ):</p> <ul> <li>HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint</li> <li>NoWarningNoElevationOnInstall = 0 (DWORD) or not defined (default setting)</li> <li>UpdatePromptSettings = 0 (DWORD) or not defined (default setting)</li> </ul> <p><strong>Having NoWarningNoElevationOnInstall set to 1 makes your system vulnerable by design.</strong></p> <p>UPDATE July 6, 2021: Microsoft has completed the investigation and has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability. See also <a href="https://support.microsoft.com/topic/CVE Program source">KB5005010: Restricting installation of new printer drivers after applying the July 6, 2021 updates</a>.</p> <p>Note that the security updates released on and after July 6, 2021 contain protections for CVE-2021-1675 and the additional remote code execution exploit in the Windows Print Spooler service known as “PrintNightmare”, documented in CVE-2021-34527.</p>
- State
- PUBLISHED
- Published
- Jul 2, 2021
- Updated
- Jan 12, 2026
- Evidence coverage
- 91%
Evidence chronology
What was known when
- Source dateSource date omittedFirst observed by CASCACISA-ADPOriginal evidence ↗
Record text: CISA ADP Vulnrichment
Inspect raw assertion
- Field
container- Value
- CISA ADP Vulnrichment
- Source dateSource date omittedFirst observed by CASCACVE ProgramOriginal evidence ↗
Record text: CVE Program Container
Inspect raw assertion
- Field
container- Value
- CVE Program Container
- Source dateSource date omittedFirst observed by CASCAmicrosoftOriginal evidence ↗
Record text: Windows Print Spooler Remote Code Execution Vulnerability
Inspect raw assertion
- Field
container- Value
- Windows Print Spooler Remote Code Execution Vulnerability
- Source dateFirst observed by CASCACISA KEVOriginal evidence ↗
Exploitation cataloged: Microsoft Windows Print Spooler Remote Code Execution Vulnerability
Inspect raw assertion
- Field
observed_exploitation- Value
- Microsoft Windows Print Spooler Remote Code Execution Vulnerability
- Source dateFirst observed by CASCAFIRST EPSSOriginal evidence ↗
EPSS score: 99.76% probability · 99.96th percentile
Inspect raw assertion
- Field
model_probability- Value
- Probability 0.997590000000; percentile 0.999550000000
FIRST EPSS · score date Aug 9, 2026 · 100th percentile · first observed Aug 9, 2026
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-v1Eligible evidence is present for this bounded claim.
- Revision
- evidence-policy-v1.1.0
- Cutoff
- Aug 27, 2026
- Resolution
- None
Eligible evidence is present for this bounded claim.
- Revision
- evidence-policy-v1.1.0
- Cutoff
- Aug 27, 2026
- Resolution
- None
Eligible evidence is present for this bounded claim.
- Revision
- casca-direct-cvss-eligibility-v1
- Cutoff
- Aug 27, 2026
- Resolution
- None
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 ADP Vulnrichment
Inspect raw assertion
- Field
container- Value
- CISA ADP Vulnrichment
CVE Program Container
Inspect raw assertion
- Field
container- Value
- CVE Program Container
Windows Print Spooler Remote Code Execution Vulnerability
Inspect raw assertion
- Field
container- Value
- Windows Print Spooler Remote Code Execution Vulnerability
Microsoft Windows Print Spooler Remote Code Execution Vulnerability
Inspect raw assertion
- Field
observed_exploitation- Value
- Microsoft Windows Print Spooler Remote Code Execution Vulnerability
99.76% probability · 99.96th percentile
Inspect raw assertion
- Field
model_probability- Value
- Probability 0.997590000000; percentile 0.999550000000
Applicability
Cited product scope
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 2026-07-21T06:45:29.809Z
27d65b0f-b718-4b4f-bb79-c47c68d09dfa - Cpe match643,502 records · observed through 2026-07-21T08:13:17.697Z
955dae73-7302-438b-aee1-058d7cc5d48e
41 scope groups
Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.10240.18969", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.14393.4470", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.2029", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19042.1083", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19044.1415", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19045.2251", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.22000.318", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.22621.674", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.3.0", "lessThan": "6.3.9600.20046", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.1.0", "lessThan": "6.1.7601.25633", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.0.0", "lessThan": "6.1.7601.25633", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.0.0", "lessThan": "6.0.6003.21138", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.0.0", "lessThan": "6.0.6003.21138", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.0.0", "lessThan": "6.0.6003.21138", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.2.0", "lessThan": "6.2.9200.23383", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.3.0", "lessThan": "6.3.9600.20046", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.3.0", "lessThan": "6.3.9600.20046", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "6.2.0", "lessThan": "6.2.9200.23383", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.14393.4470", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.14393.4470", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.2029", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.17763.2029", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.20348.230", "versionType": "custom"}]Canonical linkage remains open; the cited source assertion is retained below.
Inspect raw assertion
[{"status": "affected", "version": "10.0.0", "lessThan": "10.0.19042.1083", "versionType": "custom"}]product-9851bd571b8ab08bca589cd73710badfef557d036f0fb7707f694f1c9f597cb4Linked exactInspect raw assertion
cpe:2.3:o:microsoft:windows_10_1507:*:*:*:*:*:*:*:*- Official link
- Linked exact
- Role
- Vulnerable target
- Configuration
- 0 · node/0 · match 0
- Logic
- OR
- Version bounds
- through excluding 10.0.10240.18969
- Match ID
8c882409-bb85-490b-9d50-571b16c0de86
Affected-product evidence
Accepted scope and product mapping
17 canonical links · 1 source-reported links
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
19dd1205-63cf-453a-9ffb-9720b80403c5vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-076c7e47c78d9425d54dea0b063ed7cd79e5f9f0bfdb3c9153b8aec4e71a7ad9
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
8c9410bb-ae16-4a94-862a-9c93f6f738c0vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-217b1ab3d25f361a639824f86753d418b35aa2a816ee370bb71b5d1dd883d87a
- Source class
- Nvd cpe vulnerable target
- Assertions
- 2
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
cf2815a6-66bd-4c6d-a92e-203c6a925c2ad964a746-b8e6-4159-a0f9-61b5ac31c79bvendor-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
870e7aab-d839-4f68-87c6-d2936b6504c1vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-457c0c3b89fb1cf896e8491223eac8b0cb1ea61ce3174f915e4fe1032759d5a2
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
470670c6-2230-4ca0-9aed-1699e14e5475vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-55e90faed8848f3d316cf702d119e83086b6dc5a963d9947a7df1c589f50346d
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
c2f3c6c5-491b-4042-a4ee-8bece4bf46ecvendor-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
3607fd53-b81a-4d30-8abc-7a65fdf4145cc230294d-54a1-4800-a5a0-09a60ea311bavendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-740fec3e9838b5eabe76ebe27e4d0d7a4cb2e0ef7e13923300d3d0b51e3fce1c
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
c8e39af6-235e-42da-b4a6-7e85c328ca11vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-7e46de82012029583622f69d79b86bc210b5bd25b8cb3bb4468936702b23c4b0
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
6e49ae63-b01d-4dd2-8c8d-42ffea1f823dvendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-7fe28b5b5b17e017d9554204df059dd619746ffb5c80da87bcbfb1c52720d2f4
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
063e337d-00a8-4af1-ba02-d0881c3b22d6vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-9851bd571b8ab08bca589cd73710badfef557d036f0fb7707f694f1c9f597cb4
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
06756e2a-9670-4bc7-af4f-7eba472874f8vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-a3084138383423221f61594e86f5b295e5e254acd7ae5284f45e0877a084db43
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
5a70bcc2-ec4e-4e07-a8e1-af0f4efa4b8bvendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-a6295b9daad3ca57ce70751badba5b7fe99229c8a562cc7400e8cfef3daccaee
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
81a42d8b-9174-4a5b-a0ae-48bc2f4d6452vendor-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
8c81a2fc-3c42-4aa6-8143-4255be0419e0vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-ec10c9f400f23fdf118887f60fe116ffde4adb76dcf118cdd3a7556fd033da3b
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
d0c28252-9c2d-43ee-acef-6a07f5f0b23evendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-f20a05098a41a238f96b56b817d0482887bb39ad40620198bbe05da10ee02ffc
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
dfe78f34-e298-4a6e-880e-ba60a6482791vendor-01299a5a765aea70faa05f2d06e0c26a5d498fd34553e868d89e8a43b31864db · product-f8c509b6ec25f2a4338a23556be321da5a7c3e8da9f1a4c52f7f15dd0e9a0d2a
- Source class
- Nvd cpe vulnerable target
- Assertions
- 1
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
c8f45151-1cce-4435-ab60-addc149a2d5bCanonical 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
- 24
- Mapping revision
- cpe23-exact-mapping-v1
- Observed cutoff
- Aug 27, 2026
Retained assertion IDs
21f43ba8-3b9d-4889-a903-e51dbb686ded2711803f-06dc-4017-b802-2c09ad5f498c349295a0-c84b-41fb-a2b3-cc856f9e7cb13502c7d9-4d2e-4e94-9d1f-b9a039744e973b2cd291-b0e4-477f-ab22-dd0e9c211e55401f90b4-0143-4da8-98c7-a304d073283b449aca95-bb80-4cb0-8678-cf487bc9ae23465506c1-d54e-4e3b-a757-84d9779172c04bd97b15-cfa6-44ed-a130-8a76889f4cea57c51a18-cd1b-4104-b64d-a4a62ffd87736b3284bb-e377-4dc6-870f-f090a0ea752f7a6720d2-5d75-4b6d-a838-e410cc0570507eedaaa6-3fc0-4057-a768-1e4a272a20d090568d69-d427-46b2-8d42-b9ec13f7436893546e9c-0407-40dd-baea-65a74d89765e979bc2d5-d47a-4d4b-904e-e932371502c8ad3b5b29-24bd-4a12-99e7-9d483c9ce7adc88592da-ee42-41aa-a761-412b8dec158ddcf5aef2-466a-4b31-8d1d-9b35fbb9424ede4c0541-07e0-43fa-982d-160b23f8271bea1fa542-6459-4231-8110-ba766464419af118be4c-bf38-4b9e-b062-1d82884adae7f282bfa7-9d7f-4dfe-bb51-e9eb9a926a6cf9e9e115-1fb7-4a04-811a-3b358f45ccd1Assessments
CVSS by origin
AV:N/AC:L/Au:S/C:C/I:C/A:CCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:CDirect CVE/CNA normalized decisions
microsoft
CVSS 3.1 · Primary · Original assertion · rank 1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C- Validation
- Valid match
- Recomputed
- 8.8
- 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.