Vulnerability · Published Oct 16, 2025 · Assigned by TQtC
CVE-2025-6338Possible denial of service with multiple incoming connections to a Schannel based server with a TLS backend
Critical 9.2
In plain English
A critical-severity security flaw in Qt from Qt. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities).
Severity (CVSS 4.0)9.2Critical
Exploit odds (30 days)0.4%top 62.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
There is an incomplete cleanup vulnerability in Qt Network's Schannel support on Windows which can lead to a Denial of Service over a long period. This issue affects Qt from 5.15.0 through 6.8.3, from 6.9.0 before 6.9.2.
Affected products (as reported)
Weakness: CWE-459 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H