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Threats / Microsoft / CVE-2020-0878
CVE-2020-0878 · EUVD no mirror located · GCVE no mirror located Verified 2026-06-22

Microsoft Edge and Internet Explorer vulnerability

Memory corruption vulnerability in Microsoft Edge and Internet Explorer allows code execution in the current user's context. Actively exploited in ransomware campaigns.

Verdict

Today item, not a backlog item.

A memory corruption flaw (CWE-787) in Edge and Internet Explorer enables arbitrary code execution with user privileges. The vulnerability has been observed in active ransomware operations, presenting significant risk to affected systems.

CISA KEV Yes · 2021-11-033Ransomware use Flagged3EPSS 0.02696 (verify live)4
01

Is it exploitable?

— the evidence, ranked above the score
Reported exploitation
1 independent public report of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
cisa.gov ↗Confirmed
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), flagged for known ransomware use.
CISA KEV ↗Confirmed
Probability (EPSS)
EPSS 0.02696 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Microsoft, Edge and Internet Explorer. Confirm exact fixed builds in the vendor advisory.
NVD ↗Reported
Weakness (CWE)
Mapped to CWE-787 Out-of-bounds Write — weakness family: Memory safety.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
NVD ↗Reported
WeaknessCWE-787 · Out-of-bounds WriteMemory safety
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
Craft a malicious webpage or email link that triggers memory corruption when processed by the vulnerable browser.
Business
End users become infection vectors; ransomware deploys with user-level access to sensitive files and network resources.
2

Keys to the kingdom — privilege/identity takeover narrative 2

Attacker
Execute arbitrary code within the browser process to establish persistence or download additional payloads.
Business
Attackers gain foothold for lateral movement, credential theft, and encryption of critical business data.
3

Lateral reach — past segmentation narrative 3

Attacker
Escalate privileges or pivot to network shares and connected systems using compromised user credentials.
Business
Ransomware spreads across enterprise infrastructure, encrypting files and demanding payment for decryption keys.
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)
  • Ransomware-use flag (CISA)
  • EPSS probability (FIRST)
  • 1 reported-exploitation source(s)
  • CWE weakness mapping (NVD)
  • 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.