Threats / Microsoft / CVE-2021-1675
CVE-2021-1675
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-09-19
Microsoft Windows vulnerability
Microsoft Windows Print Spooler remote code execution vulnerability enabling unauthenticated attackers to execute arbitrary code with system privileges.
Verdict
Today item, not a backlog item.
Critical vulnerability in Windows Print Spooler service allowing remote code execution without authentication. Actively exploited in ransomware campaigns. Requires immediate patching across all affected Windows systems.
CISA KEV Yes · 2021-11-035Ransomware use Flagged5EPSS 0.86132 (verify live)6Exploit Weaponized · public PoC7CVSS 7.83CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Fully weaponized — public exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
27 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 2021-11-03), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.86132 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.8 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C) · Affected: Microsoft, Windows. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-285 Improper Authorization — weakness family: Authorization / access control.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 148 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a functional/weaponized public exploit). Catalog entries: Metasploit module. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
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 identify and target Windows systems with exposed or accessible Print Spooler services.
Business
Attackers gain initial network access to enterprise infrastructure without requiring valid credentials.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I send specially crafted requests to the Print Spooler service to trigger remote code execution.
Business
Malicious code executes with SYSTEM-level privileges, bypassing application-level security controls.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistent access and deploy ransomware or data exfiltration tools across the compromised environment.
Business
Ransomware operators encrypt critical business data and systems, demanding payment for decryption keys.
4
Data at risk — exfiltration narrative 4
Attacker
I propagate laterally through the network using compromised credentials and system access.
Business
Breach scope expands to multiple systems and departments, increasing recovery costs and operational downtime.
5
Lights out — disruption & extortion narrative 5
Attacker
I maintain access through backdoors while exfiltrating sensitive data and intellectual property.
Business
Organizations face regulatory fines, reputational damage, and long-term business disruption from data loss.
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
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by microsoftCNA
Credited with finding itYunhai Zhang of NSFOCUS TIANJI LAB https://www.nsfocus.com.cn/finderPiotr Madej of AFINEfinderZhipeng Huo (@R3dF09) of Tencent Security Xuanwu Labfinder
Found an error? Propose a correction.
A correction is a cited counter-claim — it must cite a source,
gets reviewed by a second human, and is never auto-applied. See the
correction convention and our identity
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