CVE-2021-26411

Exploitation

Exploited in the wild. Listed in the CISA Known Exploited Vulnerabilities catalog on 2021-11-03. Federal remediation due 2021-11-17.

SSVC decision

• ExploitationactiveCISA reports credible evidence of active exploitation.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

80.77% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 99.6% of scored records. A rank, not a probability.

NVD base score

8.8 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L

NVD analysis status

Analyzed. NVD last modified this record on 2026-08-19.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-03-11 15:07Z5 YR AGO

Last updated

2026-08-19 16:30Z16 DAYS AGO

Reserved

2021-01-29

Assigning CNA

microsoft

Record state

PUBLISHED

Severity

High (CVSS 8.8)

CNA CVSS 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

Weaknesses

• CWE-416Use After FreeVariant

Data version

5.2

Document digest

b46d3c5345e65973fde7ace4fd92e70395444a5f21f33dee40afe7e3d767fcbc

• msrc.microsoft.comInternet Explorer Memory Corruption Vulnerabilityhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26411vendor-advisorypatch
• portal.msrc.microsoft.comhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26411x_refsource_MISC
• www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26411government-resource