Cyber Resilience

CVE-2020-0878

Memory Safety in Microsoft Internet Explorer 11 … 9

CISA KEVActive ExploitationEUVD ExploitedRansomware-linkedMemory Safety
Published
11 September 2020
Modified
23 February 2026
KEV Added
03 November 2021
Patch / advisory
CVSS Score v3.1 4.2
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
EPSS Score 0.027 85th percentile
Risk Priority 75 floored blend · peak EPSS

Summary

CVE-2020-0878 is a medium-severity Out-of-bounds Write (CWE-787) vulnerability in Microsoft Internet Explorer. Its CVSS base score is 4.2 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 15% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

A remote code execution vulnerability exists in Microsoft browsers due to improper handling of objects in memory. Successful exploitation can corrupt memory and allow an attacker to execute arbitrary code in the context of the current user, potentially leading to full system compromise if the user has administrative rights. The issue is tracked under CWE-787 and carries a CVSS score of 4.2.

An attacker can exploit the flaw by hosting a specially crafted website and convincing a user to visit it, often through email, instant messaging, or compromised sites that serve malicious content or ads. No user action beyond viewing the page is forced, but the attacker must rely on social engineering to succeed. Once exploited, the attacker gains the same privileges as the logged-in user.

The official security update mitigates the vulnerability by changing how Microsoft browsers handle objects in memory, as described in the Microsoft Security Response Center advisory. The CVE is referenced in the CISA Known Exploited Vulnerabilities catalog.

EU & UK References

Vulnerability Data

<p>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.…

more

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.</p> <p>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.</p> <p>The security update addresses the vulnerability by modifying how Microsoft browsers handle objects in memory.</p>

CWE(s)
KEV Date Added
03 November 2021

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
T1211 Exploitation for Stealth Stealth
Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2020-1380Same product: Microsoft Internet Explorerboth on KEV
CVE-2020-0968Same product: Microsoft Internet Explorerboth on KEV
CVE-2020-1020Same product: Microsoft Windows 10 1507both on KEV
CVE-2018-8653Same product: Microsoft Internet Explorerboth on KEV
CVE-2019-1367Same product: Microsoft Internet Explorerboth on KEV
CVE-2020-1027Same product: Microsoft Windows 10 1507both on KEV
CVE-2020-0938Same product: Microsoft Windows 10 1507both on KEV
CVE-2020-1054Same product: Microsoft Windows 10 1507both on KEV
CVE-2021-33742Same product: Microsoft Windows 10 1507both on KEV
CVE-2021-34448Same product: Microsoft Windows 10 1507both on KEV

Affected Assets

microsoft
internet explorer
11, 9
microsoft
edge
all versions
microsoft
chakracore
all versions

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-787

Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure-development practices (static analysis, bounds checking, code review) are the primary means of preventing out-of-bounds writes.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover out-of-bounds write flaws so they can be remediated.

PR.PS-02 partial match
prevents

Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

finds

Security testing in development and acceptance can detect and prevent out-of-bounds write defects.

prevents

Secure development life cycle mandates practices that prevent out-of-bounds writes.

prevents

Application security requirements can specify bounds-checking and safe memory handling.

prevents

Secure architecture and engineering principles reduce the likelihood of buffer overflows.

prevents

Secure coding directly addresses out-of-bounds writes through language choice and coding standards.

prevents

Change management can enforce review gates that catch unsafe memory operations before deployment.

References