Security readout for executives and security teams
Plain-English summary
A user who opens malicious web content in Internet Explorer 11 could enable remote code execution. Successful exploitation may let an attacker alter data and disrupt the affected system. CISA lists this CVE as known exploited, making unresolved legacy-browser exposure an urgent concern.
Executive priority
Treat as a high-priority legacy exposure because exploitation is documented and compromise can materially affect system integrity. Direct teams to identify remaining Internet Explorer dependencies, apply Microsoft’s applicable update, and escalate unsupported or unpatchable systems.
Technical view
CVE-2021-27085 is an Internet Explorer 11 remote-code-execution vulnerability rated CVSS 8.8. The vector indicates network reachability, low attack complexity, no required privileges, required user interaction, and changed security scope. The bundle reports high integrity impact with lower confidentiality and availability impacts.
Likely exposure
Systems retaining Internet Explorer 11 or components that invoke its legacy browsing engine may warrant review. The supplied affected-version value, “1.0.0,” is not credible version guidance, so exact affected builds cannot be established from this bundle alone.
Exploitation context
CISA KEV inclusion supports active exploitation in the wild. Exploitation still requires user interaction according to the CVSS vector. The supplied sources do not describe campaigns, attack volume, exploit reliability, or whether exploitation remains widespread.
Researcher notes
The bundle provides only a generic vulnerability description and no CWE, root cause, affected build matrix, or attack-chain detail. Its “1.0.0” version entry appears unreliable. Use the Microsoft advisory as the authority for build applicability and remediation; do not infer undocumented affected products.
Mitigation direction
- Apply the applicable Microsoft security update identified by the MSRC advisory.
- Check current Microsoft guidance to determine affected builds and required update packages.
- Restrict or retire Internet Explorer 11 where business dependencies permit.
- Reduce access to untrusted web content from systems retaining legacy browser dependencies.
Validation and detection
- Inventory systems where Internet Explorer 11 remains installed, enabled, or operationally required.
- Compare installed Microsoft updates against the CVE-2021-27085 MSRC advisory.
- Review application dependencies that may invoke Internet Explorer or its legacy rendering components.
- Confirm compensating controls and retirement plans for systems that cannot be promptly updated.
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.
Execution 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-2021-27085 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
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L/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
SSVC decision data
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:L/PR:N/UI:R/S:C/C:L/I:H/A:L/E:P/RL:O/RC:C2.85.3microsoftVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L/E:P/RL:O/RC:C
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- ADP timelineCISA-ADP
CVE-2021-27085 added to CISA KEV
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2021-11-03T00:00:00.000Z: CVE-2021-27085 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- Internet Explorer Remote Code Execution VulnerabilityCVE reference, microsoft · vendor-advisory, patch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-27085CVE reference, CVE · x_refsource_MISC, x_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27085CVE reference, CISA-ADP · 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.