Threats / Microsoft / CVE-2021-41379
CVE-2021-41379
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Microsoft Windows vulnerability
Microsoft Windows Installer privilege escalation vulnerability enabling unauthorized system-level access through unspecified attack vector.
Verdict
Today item, not a backlog item.
Critical elevation-of-privilege flaw in Windows Installer actively exploited in ransomware campaigns. Attackers gain SYSTEM privileges to deploy malware, encrypt data, and establish persistence. Immediate patching required.
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
4 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-03), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.20255 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Microsoft, Windows. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-1386 CWE-1386.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
WeaknessCWE-1386 · CWE-1386
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious installer package or trigger a Windows Installer operation to exploit the privilege escalation flaw.
Business
Attacker obtains SYSTEM-level code execution on the target machine.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I use elevated privileges to disable security controls, modify system files, and establish persistence mechanisms.
Business
Ransomware payload deploys undetected and becomes difficult to remove.
3
Lateral reach — past segmentation narrative 3
Attacker
I encrypt critical business data and demand ransom payment for decryption keys.
Business
Organization suffers data unavailability, operational disruption, and financial extortion losses.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05