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

Internet Explorer Memory Corruption Vulnerability

01What is this vulnerability?

Internet Explorer Memory Corruption Vulnerability

02Affected products

03Active exploitation status

Yes — actively exploited. Added to the CISA KEV catalog on 2021-11-03. Ransomware use: Known.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:

Open in Sigma generator →

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2021-03-11T15:07:28.000Z
• Last modified: 2025-10-21T23:25:52.201Z
• Added to CISA KEV: 2021-11-03
• BOD 22-01 due: 2021-11-17

09References

• portal.msrc.microsoft.com — https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-2641…