CVE-2026-55991: Remote DNS-over-QUIC (DoQ) flow-control assertion failure in libngtcp2

Overview

Severity

Medium (CVSS 5.9)

CVSS Vector

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

Exploit Status

Not Exploited

Patch Tuesday

2026-Jul

Released

2026-07-23

Affected Products (1)

Other

• 21595-17084

Revision History

• 2026-07-23: Information published.