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Vulnerabilities

Vulnerability · CVE-2021-26411

Microsoft Internet Explorer Memory Corruption Vulnerability

Published Mar 9, 2021 · catalog updated Oct 1, 2026 · Microsoft Internet Explorer

Patch now

CVE-2021-26411 is in the CISA known-exploited catalog, due Nov 17, 2021. Confirm Microsoft Internet Explorer against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
High8.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
80.77%
Remediation
Remediation guidance
Affected products
cpe microsoft/edge · cpe microsoft/internet explorer · vendor Microsoft Internet Explorer

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

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe microsoft/edgeversion unspecified
  • cpe microsoft/internet explorer11
  • cpe microsoft/internet explorer9
  • vendor Microsoft Internet Explorerversion unspecified

How to fix CVE-2021-26411

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2021-26411 is in the CISA known-exploited catalog, due Nov 17, 2021. Confirm Microsoft Internet Explorer against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with microsoft/internet explorer 11; microsoft/internet explorer 9. Apply updates per vendor instructions.

What should an analyst verify?

CWE-416: Use After Free. EPSS 80.77%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 11, 2021 · Catalog

    Detected

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

  2. Nov 3, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Nov 17, 2021 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Oct 1, 2026 · Catalog

    Updated

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

Sources

  • CISA KEVConfirmed exploitationCVE-2021-26411

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

    cisa.gov
  • CVE.orgVulnerability recordCVE-2021-26411

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-26411

    30-day exploitation probability 80.8%

    first.org
  • NIST NVDVulnerability recordCVE-2021-26411

    Internet Explorer Memory Corruption Vulnerability

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2021-26411

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

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.