VulnTideExploited vulnerabilities, by vendor. Data as of 28 Oct 2026.
Known exploitedIn CISA's KEV catalog since 3 November 2021Ransomware use: known
Microsoft Internet Explorer

CVE-2021-26411: Microsoft Internet Explorer Memory Corruption Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, 237 days after the CVE record was published.

How likely is exploitation in the next 30 days?
81.7%

EPSS score, percentile 99.6 of all scored records

How severe?
8.8 High

CVSS v3.1 base score, given by the CNA

What should I do?

CISA deadline 17 Nov 2021. Apply updates per vendor instructions.

Advisories and patches (1)

Which versions are affected?

Affected

  • from 1.0.0 to before 10.0.17134.2087
  • from 1.0.0 to before 6.0.6003.21070
  • from 1.0..0 to before 10.0.17134.2087

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

Required action, set by CISA

Apply updates per vendor instructions.

CISA due date for this action: 17 November 2021.

Advisories and patches

Linked from CISA's catalog entry

Affected products and versions

As listed in the CVE record.

Microsoft Internet Explorer 11
StatusVersions
Affectedfrom 1.0.0 to before 10.0.17134.2087
Microsoft Internet Explorer 9
StatusVersions
Affectedfrom 1.0.0 to before 6.0.6003.21070
Microsoft Microsoft Edge (EdgeHTML-based)
StatusVersions
Affectedfrom 1.0..0 to before 10.0.17134.2087

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Microsoft Internet Explorer contains an unspecified vulnerability that allows for memory corruption.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

  • CISA added CVE-2021-26411 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Nov 2021.
  • CISA marks it as known to be used in ransomware campaigns.
  • The due date CISA sets for the required action is 17 Nov 2021.
  • The CVE record was published on 11 Mar 2021, 237 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 8.8 (High), given by its CNA.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 81.7% (percentile 99.6), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact partial.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

Internet Explorer Memory Corruption Vulnerability

Internet Explorer Memory Corruption Vulnerability

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

DateEvent
11 Mar 2021CVE record published
3 Nov 2021Added to CISA KEV
17 Nov 2021CISA due date for the required action
1 Oct 2026CVE record last updated

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