CVE-2021-26411
HighExploitedPublic exploitInternet Explorer Memory Corruption Vulnerability
Published Mar 11, 2021 · Updated Oct 1, 2026
Key Facts
Patch immediately- CVE-2021-26411 is a high-severity vulnerability (CVSS 8.8 v3.1) affecting Edge (Microsoft), Internet Explorer (Microsoft), Internet Explorer 11 and 2 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Mar 9, 2021 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 81% probability of exploitation in the next 30 days.
- Fixed versions are available, including Internet Explorer 11 10.0.17134.2087, Internet Explorer 9 6.0.6003.21070, Edge 10.0.17134.2087.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
8.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
81%
Higher than 99.6% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2021-26411 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
Internet Explorer Memory Corruption Vulnerability
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| Industry KEV feed | Mar 9, 2021 | Nov 17, 2021 | Known |
| CIRCL KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
9 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| EdgeMicrosoft | See advisory | 10.0.17134.2087 |
| Internet ExplorerMicrosoft | 11, 9 | 6.0.6003.21070 |
| Internet Explorer 11 | >= 1.0.0 | 10.0.17134.2087 |
| Internet Explorer 9 | >= 1.0.0 | 6.0.6003.21070 |
| Microsoft Edge (EdgeHTML-based) | >= 1.0..0 | 10.0.17134.2087 |
Patched Releases
Internet Explorer 11
10.0.17134.2087
Internet Explorer 9
6.0.6003.21070
Edge
10.0.17134.2087, publication
Microsoft Edge (EdgeHTML-based)
10.0.17134.2087
Internet Explorer
10.0.17134.2087, 6.0.6003.21070, publication
Timeline
Added to Industry KEV feed
Mar 9, 2021
Publicly disclosed
Mar 11, 2021
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Oct 1, 2026
Weakness Type
- CWE-416 Use After Free
References
- patchhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26411
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
Internet Explorer Memory Corruption Vulnerability
Affected: Edge (Microsoft); Internet Explorer (Microsoft) versions 11, 9; Internet Explorer 11 versions >= 1.0.0, among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Mar 9, 2021 and is known to be used in ransomware campaigns.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of Nov 17, 2021.
Public exploit code is available.
Fixed versions are available, including Internet Explorer 11 10.0.17134.2087, Internet Explorer 9 6.0.6003.21070, Edge 10.0.17134.2087.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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