CVE-2026-21265

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

• ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpacttotalSuccessful exploitation gives total 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

1.09% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 65.1% of scored records. A rank, not a probability.

NVD base score

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

NVD CVSS vector

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

NVD analysis status

Analyzed. NVD last modified this record on 2026-07-30.

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

2026-01-13 17:56Z9 MO AGO

Last updated

2026-07-30 20:46Z3 MO AGO

Reserved

2025-12-11

Assigning CNA

microsoft

Record state

PUBLISHED

Severity

Medium (CVSS 6.4)

CNA CVSS vector

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Weaknesses

• CWE-1329Reliance on Component That is Not UpdateableBase

Data version

5.2

Document digest

bb8ada24ab0aa5f4e8325a64a3485120aca0533199fd7c59bbf5b5a4d6be80c1

• msrc.microsoft.comSecure Boot Certificate Expiration Security Feature Bypass Vulnerabilityhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21265vendor-advisorypatch