basicsecurity.net
Proof, not just disclosure.
Threats / Microsoft / CVE-2021-31199
CVE-2021-31199 · EUVD no mirror located · GCVE no mirror located Verified 2026-06-22

Microsoft Enhanced Cryptographic Provider vulnerability

Microsoft Enhanced Cryptographic Provider contains an unspecified privilege escalation vulnerability that has been exploited in the wild.

Verdict

Today item — known-exploited.

A privilege escalation flaw in Microsoft's Enhanced Cryptographic Provider enables attackers to gain elevated system access. Active exploitation in the wild indicates immediate risk to affected systems.

CISA KEV Yes · 2021-11-033EPSS 0.02954 (verify live)4
01

Is it exploitable?

— the evidence, ranked above the score
Reported exploitation
5 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).
CISA KEV ↗Confirmed
Probability (EPSS)
EPSS 0.02954 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Microsoft, Enhanced Cryptographic Provider. Confirm exact fixed builds in the vendor advisory.
NVD ↗Reported
02

Who’s exploiting it?

— attribution turns risk into urgency
Attribution 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 board
1

Front door — unauthenticated access narrative 1

Attacker
I identify and exploit a privilege escalation weakness in the Enhanced Cryptographic Provider to elevate my access level on the target system.
Business
An attacker gains administrative or system-level privileges, enabling full system compromise and lateral movement within the network.
2

Keys to the kingdom — privilege/identity takeover narrative 2

Attacker
I use elevated privileges to install persistent backdoors, modify system configurations, or exfiltrate sensitive data.
Business
The organization faces data breach, system integrity compromise, and potential regulatory violations from unauthorized access to protected information.
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’t

Established (cited)

  • KEV listing (CISA)
  • EPSS probability (FIRST)
  • 5 reported-exploitation source(s)
  • Catalogued by microsoft (CNA)
  • Coverage gaps — stated, not hidden

  • No EUVD / GCVE mirror in feed — single-authority dependency for the identifier.
  • EPSS & exposure are time-varying; verify live at the source.
  • Threat-actor attribution not established from feed data — absence of a name is not absence of compromise.
  • No finder/reporter credit recorded in the public CVE entry — the work behind this find is unattributed.
  • Disclosure & credit2
    Catalogued by microsoftCNA
    Credited with finding itNo finder named in the public CVE record — the work behind this find is unattributed.