Vulnerability · Published Sep 16, 2026 · Assigned by Qt
CVE-2026-76151Out-of-bounds read (buffer over-read) vulnerability in HTTP Cache-Control response header parsing impacts Qt Framework (QtNetwork module)
Medium 4.6
In plain English
A medium-severity out-of-bounds read 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 0.7% (higher than 52% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | qt6-base | no fix listed | DEBIAN-CVE-2026-76151 |
| Debian:13 | qt6-base | no fix listed | DEBIAN-CVE-2026-76151 |
| Debian:14 | qt6-base | 6.11.2+dfsg-5 | DEBIAN-CVE-2026-76151 |
| Ubuntu:22.04:LTS | qt6-base | no fix listed | UBUNTU-CVE-2026-76151 |
| Ubuntu:24.04:LTS | qt6-base | no fix listed | UBUNTU-CVE-2026-76151 |
| Ubuntu:26.04:LTS | qt6-base | no fix listed | UBUNTU-CVE-2026-76151 |
| Ubuntu:26.10 | qt6-base | no fix listed | UBUNTU-CVE-2026-76151 |
| Ubuntu:26.04:LTS | qtbase-opensource-src | no fix listed | UBUNTU-CVE-2026-76151 |
| Ubuntu:26.10 | qtbase-opensource-src | no fix listed | UBUNTU-CVE-2026-76151 |
Affected products (as reported)
Weakness: CWE-125, CWE-197 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/AU:N/R:A