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 products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| qt | qt | 6.0.0 – < 6.8.9, 6.9.0 – < 6.11.2 | 6.8.9 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | qt6-base | 6.11.2+dfsg-5 | — |
| Debian 13 | qt6-base | No fix yet | — |
| Debian 12 | qt6-base | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | qt6-base +1 | No fix yet | — |
| Ubuntu 26.04 LTS | qt6-base +1 | No fix yet | — |
| Ubuntu 24.04 LTS | qt6-base | No fix yet | — |
| Ubuntu 22.04 LTS | qt6-base | No fix yet | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | qtbase-opensource-src | No fix yet | — |
| Ubuntu Pro 22.04 LTS | qtbase-opensource-src | No fix yet | — |
| Ubuntu Pro 20.04 LTS | qtbase-opensource-src | No fix yet | — |
| Ubuntu Pro 18.04 LTS | qtbase-opensource-src | No fix yet | — |
| Ubuntu Pro 16.04 LTS | qtbase-opensource-src | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | AusweisApp | 2.6.0-1.1 | openSUSE-SU-2026:12071-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | qt5-qtbase +9 | 5.15.3-1.amzn2.0.4 | ALAS2-2026-3980 |
Advisories 3
- WID-SEC-2026-3383 QT: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Nov 11, 2026
- ALAS2-2026-3980 Important: qt5-qtbase security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Oct 12, 2026
- openSUSE-SU-2026:12071-1 AusweisApp-2.6.0-1.1 on GA media SUSE / openSUSE Security Updates · Oct 9, 2026