CVE-2021-38593

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 3.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-08-12 · updated 2026-06-17
Weakness: CWE-787

Description

Qt 5.x before 5.15.6 and 6.x through 6.1.2 has an out-of-bounds write in QOutlineMapper::convertPath (called from QRasterPaintEngine::fill and QPaintEngineEx::stroke).

Affected products

Fedoraproject Fedora: 35, 36
Qt: from 5.0.0 before 5.15.6; from 6.0.0 through 6.1.2 — fixed in 5.15.6

How to fix

Upgrade to a fixed version: Qt 5.15.6. Check the vendor advisory for mitigations.

References

https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35566
https://github.com/google/oss-fuzz-vulns/blob/main/vulns/qt/OSV-2021-903.yaml
https://github.com/qt/qtbase/commit/1ca02cf2879a5e1511a2f2109f0925cf4c892862
https://github.com/qt/qtbase/commit/202143ba41f6ac574f1858214ed8bf4a38b73ccd
https://github.com/qt/qtbase/commit/6b400e3147dcfd8cc3a393ace1bd118c93762e0c
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/36VN2WKMNQUSTF6ZW2X52NPAJVXJ4S5I/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HY5YCSDCTLHVMP3OXOM6HNTWHV6DBHDX/
https://security.gentoo.org/glsa/202402-03
https://wiki.qt.io/Qt_5.15_Release#Known_Issues
https://www.qt.io/blog/qt-5.15-extended-support-for-subscription-license-holders
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35566
https://github.com/google/oss-fuzz-vulns/blob/main/vulns/qt/OSV-2021-903.yaml

Get alerted when CVE-2021-38593 or the next vulnerability affects your stack