CVE intelligence

CVE-2026-102559

Vulnerability intelligence

Published Sep 29, 2026Sources checked Oct 4, 2026

8.6HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-102559 and is rated High severity with a CVSS score of 8.6. 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

Release Notes

CISA KEVNot listedBased on the latest collected catalog

EPSS0.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-102559?

A flaw was found in libsoup. When constructing a masked WebSocket client frame for a very large outgoing payload, size values passed to GByteArray allocation APIs could be truncated while the masking routine still used the full length, causing a heap buffer overflow.