CVE-2026-103963 and is rated High severity with a CVSS score of 7.5. 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
Vendor revision: Nov 3, 2026
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-2026-103963?
A flaw was found in glib-networking. When establishing connections using Transport Layer Security (TLS) version 1.3, the client-side session cache does not limit the number of session tickets retained for a single host.
A malicious server can exploit this by sending excessive session ticket messages, causing the client application to continuously consume memory. This unbounded memory growth can exhaust system memory, resulting in a Denial of Service (DoS).