CVE intelligence

CVE-2025-58186

Vulnerability intelligence

Published Oct 29, 2025Sources checked Sep 29, 2026

5.3MEDIUMCVSS out of 10

What this means

Review the available evidence

CVE-2025-58186 and is rated Medium severity with a CVSS score of 5.3. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

See the Microsoft Security Update Guide for the update that applies to your product.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.5%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2025-58186?

Despite HTTP headers having a default limit of 1MB, the number of cookies that can be parsed does not have a limit. By sending a lot of very small cookies such as "a=;", an attacker can make an HTTP server allocate a large amount of structs, causing large memory consumption.