Security readout for executives and security teams
Plain-English summary
This is a Microsoft browser memory corruption flaw that can let an attacker run code as the signed-in user after the user views attacker-controlled content. Business risk is higher where legacy Microsoft browsers remain in use, especially by administrators.
Executive priority
Treat this as a high-priority legacy browser remediation item because CISA lists it as known exploited, despite a medium CVSS score. Prioritize systems used by privileged users and environments where Internet Explorer or EdgeHTML remains operational.
Technical view
CVE-2020-0878 is a CWE-787 memory handling vulnerability in Microsoft browser object access. The bundled CVSS is 4.2: network reachable, no privileges, high attack complexity, and user interaction required. Successful exploitation can execute arbitrary code in the current user context.
Likely exposure
Exposure is most likely on systems still using Internet Explorer 9, Internet Explorer 11, EdgeHTML-based Microsoft Edge, or affected ChakraCore. Risk depends on users reaching malicious, compromised, ad-supported, or user-content websites through those technologies.
Exploitation context
CISA KEV inclusion supports known exploitation. The provided sources do not identify campaigns, exploit maturity, or affected deployment prevalence. Microsoft describes web or attachment-driven social engineering where attackers must convince users to view crafted content.
Researcher notes
Do not infer Chromium-based Edge exposure from this bundle; it names EdgeHTML-based Edge, IE 9, IE 11, and ChakraCore. Public evidence here confirms exploitation via KEV but does not provide campaign details, indicators, or exploit mechanics.
Mitigation direction
- Apply Microsoft’s security update for CVE-2020-0878 where applicable.
- Inventory and retire affected legacy Microsoft browsers where possible.
- Restrict administrative users from routine web browsing.
- Check current Microsoft guidance for product-specific remediation details.
- Reduce exposure to untrusted web content on legacy systems.
Validation and detection
- Confirm affected browser and ChakraCore versions across managed assets.
- Verify Microsoft security updates are installed on exposed systems.
- Review whether administrators use affected browsers for daily browsing.
- Check endpoint telemetry for legacy browser execution after patching.
- Confirm browser hardening policies apply to legacy Microsoft browsers.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-787: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2020-0878 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 4.2 (3.1)
- Known Exploited
- Yes
- Published
Vector: 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
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N/E:P/RL:O/RC:C1.62.5Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.2MediumVector: 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
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0878CVE reference · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-0878CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
