CVE-2026-76151: Qt

Medium severity, CVSS 4.6. EPSS: 0.7% chance of exploitation in the next 30 days.

Out-of-bounds read (buffer over-read) in the HTTP Cache-Control response header parsing in the QtNetwork module in Qt Group Qt 6.0.0 through 6.8.8, and 6.9.0 through 6.11.1, allows remote attackers to cause a denial of service (application crash) via an excessively large Cache-Control header value returned by an untrusted or compromised HTTP server to an application using QNetworkAccessManager. Only the client side of the connection is affected and 32-bit builds are not affected; the out-of-bounds access is read-only, with no information disclosure and no code execution.

Affected products

• Qt Qt: from 6.0.0, before 6.8.9 (fixed in 6.8.9); from 6.9.0, before 6.11.2 (fixed in 6.11.2)

Published 2026-09-16. Last modified 2026-09-18.