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CVE-2021-41379· NVD / CVE Program· CNA microsoft

Windows Installer Elevation of Privilege Vulnerability

MediumCVSS 5.5 · v3.1KEVWeaponized No fix recorded
Published
Nov 9, 2021
Updated
Aug 19, 2026
EPSS
19.5% · 97th percentile
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Report tools

JSON

Action score

58

Plan

Add it to your regular patch cycle.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
30 / 30 · Listed
EPSS
6 / 30 · 19.5%

CISA SSVC decision

Exploitation
active
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · microsoft
5.5
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Mar 3, 2022. That signals real attacks, not theory.

Remediation deadline for government agencies: Mar 17, 2022.

Known to be used in ransomware campaigns.

Affected systems

VendorProduct
microsoftwindows 10 1507
microsoftwindows 10 1607
microsoftwindows 10 1809
microsoftwindows 10 1909
microsoftwindows 10 2004
microsoftwindows 10 20h2
microsoftwindows 10 21h1
microsoftwindows 11 21h2
microsoftwindows 7
microsoftwindows 8.1
microsoftwindows rt 8.1
microsoftwindows server 2004

and 6 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • microsoft windows server 2004before 10.0.19041.1348
  • microsoft windows server 2008all versions
  • microsoft windows server 2008r2
  • microsoft windows server 2012all versions
  • microsoft windows server 2012r2
  • microsoft windows server 2016before 10.0.14393.4770
  • microsoft windows server 2019before 10.0.17763.2300
  • microsoft windows server 2022before 10.0.20348.350
  • microsoft windows server 20h2before 10.0.19042.1348

Versions reported by the vendor

Affected version ranges reported by the assigning authority (microsoft). Independent of NVD's CPE analysis and usually ahead of it.

  • Microsoft Windows 10 Version 1507

    • 10.0.10240.0 and later · before 10.0.10240.19119affected

  • Microsoft Windows 10 Version 1607

    • 10.0.14393.0 and later · before 10.0.14393.4770affected

  • Microsoft Windows 10 Version 1809

    • 10.0.17763.0 and later · before 10.0.17763.2300affected
    • 10.0.0 and later · before 10.0.17763.2300affected

  • Microsoft Windows 10 Version 1909

    • 10.0.0 and later · before 10.0.18363.1916affected

  • Microsoft Windows 10 Version 2004

    • 10.0.0 and later · before 10.0.19041.1348affected

  • Microsoft Windows 10 Version 20H2

    • 10.0.0 and later · before 10.0.19042.1348affected

  • Microsoft Windows 10 Version 21H1

    • 10.0.0 and later · before 10.0.19043.1348affected

  • Microsoft Windows 11 version 21H2

    • 10.0.22000.0 and later · before 10.0.22000.318affected

  • Microsoft Windows 7

    • 6.1.0 and later · before 6.1.7601.25769affected

  • Microsoft Windows 7 Service Pack 1

    • 6.1.0 and later · before 6.1.7601.25769affected

  • Microsoft Windows 8.1

    • 6.3.0 and later · before 6.3.9600.20174affected

  • Microsoft Windows Server 2008 R2 Service Pack 1

    • 6.1.7601.0 and later · before 6.1.7601.25769affected

Same product

microsoft: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-34527Windows Print Spooler Remote Code Execution VulnerabilityKEV
    95Now
  • CVE-2021-40444Microsoft MSHTML Remote Code Execution VulnerabilityKEV
    94Now
  • CVE-2025-33053Internet Shortcut Files Remote Code Execution VulnerabilityKEV
    91Now
  • CVE-2023-36025Windows SmartScreen Security Feature Bypass VulnerabilityKEV
    91Now
  • CVE-2022-30190Microsoft Windows Support Diagnostic Tool (MSDT) Remote Code Execution VulnerabilityKEV
    91Now
  • CVE-2017-8543Microsoft Windows XP SP3, Windows XP x64 XP2, Windows Server 2003 SP2, Windows Vista, Windows 7 SP1, Windows Server 2008 SP2 and R2 SP1, WinKEV
    91Now

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. CISA KEV+113 d
  3. TodaySep 29, 2026+1785 d
EPSS, last 120 days-1% in 7 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-59 · Improper Link Resolution Before File Access ('Link Following')

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records