Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2020-0878

Microsoft Browser Memory Corruption Vulnerability

Microsoft / ChakraCore · affected before publication

Severity
CVSS 4.2 · Medium
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
2.7%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2020-0878 is an unauthenticated Microsoft Browser Memory Corruption Vulnerability. A remote code execution vulnerability exists in the way that Microsoft browsers access objects in memory. The vulnerability could...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV.

Who is affected?

Microsoft / ChakraCore affected before publication.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

A remote code execution vulnerability exists in the way that Microsoft browsers access objects in memory

A remote code execution vulnerability exists in the way that Microsoft browsers access objects in memory. The vulnerability could corrupt memory in a way that could allow an attacker to execute arbitrary code in the context of the current user. An attacker who successfully exploited the vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, the attacker could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

An attacker could host a specially crafted website that is designed to exploit the vulnerability through Microsoft browsers, and then convince a user to view the website. The attacker could also take advantage of compromised websites, or websites that accept or host user-provided content or advertisements, by adding specially crafted content that could exploit the vulnerability. In all cases, however, an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically via an enticement in email or instant message, or by getting them to open an email attachment. The security update addresses the vulnerability by modifying how Microsoft browsers handle objects in memory.

Microsoft Affected
ChakraCore
Before publication
Microsoft Affected
Microsoft Edge (EdgeHTML-based)
Before publication
Microsoft Affected
Internet Explorer 9
Before publication
Microsoft Affected
Internet Explorer 11
Before publication
Published
11 Sep 2020
Exploitation Reported
03 Nov 2021
Attack vector
Remote
Complexity
High
Privileges
None
User interaction
Required

Tags

malware cisa ransomware microsoft

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 03 Nov 2021

A trusted third party reported exploitation.

Used in malware

CISA

Recorded 03 Nov 2021

Malware families have been linked to exploitation of this CVE.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CISA First 2021-11-03 00:00 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

4.2 Medium

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

2.7%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Timeline

From disclosure to observed exploitation

  1. 00:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  2. 00:00 UTC

    First public exploitation report

    Exploit observed in malware

  3. 17:08 UTC

    CVE published

    Vulnerability disclosed publicly

  4. 00:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2020-0878

Sample API response
{
  "cve_id": "CVE-2020-0878",
  "confidence": "Confirmed",
  "cvss_score": 4.2,
  "cvss_estimated": false,
  "epss_score": 0.02696,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}