CVE-2025-21418

Exploitation

Exploited in the wild. Listed in the CISA Known Exploited Vulnerabilities catalog on 2025-02-11. Federal remediation due 2025-03-04.

SSVC decision

• ExploitationactiveCISA reports credible evidence of active 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

2.13% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 81.8% of scored records. A rank, not a probability.

NVD base score

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

NVD CVSS vector

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

NVD analysis status

Analyzed. NVD last modified this record on 2026-06-17.

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

2025-02-11 17:58Z1 YR AGO

Last updated

2026-02-26 19:09Z8 MO AGO

Reserved

2024-12-11

Assigning CNA

microsoft

Record state

PUBLISHED

Severity

High (CVSS 7.8)

CNA CVSS vector

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

Weaknesses

• CWE-122Heap-based Buffer OverflowVariant

Data version

5.2

Document digest

3f85fb2f1be1fa21050b64e135a390849c5f511fb45dcbe57ead222addc15dce

• msrc.microsoft.comWindows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerabilityhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21418vendor-advisorypatch
• www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21418government-resource