setMarkdown in Qt before 5.14.2 has a use-after-free related to QTextMarkdownImporter::insertBlock.

published 2020-04-27 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-4580

cvss: 9.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 2.4%; EPSS 2.4% chance of exploitation in 30 days, percentile 84%
public exploits: 0; none known

Patch / fix

distros 1 links 1

libqt5-qtbase openSUSE Tumbleweed 5.15.2+kde222-1.3

opensuse advisories openSUSE-SU-2024:10975-1

codereview.qt-project.org/c/qt/qtbase/+/291706 advisory

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-12267 updated 2026-11-05 cvss 9.8

qt: use-after-free related to QTextMarkdownImporter::insertBlock

Red Hat Enterprise Linux 5 qt, qt4 Red Hat Enterprise Linux 6 qt, qt3, qt-x11, qt-odbc, qt-demos, qt-mysql, +10 more Red Hat Enterprise Linux 7 qt, qt3, qt-x11, qt-odbc, qt-qvfb, qt-demos, +12 more Red Hat Enterprise Linux 8 qt5, qt5-rpm-macros, qt5-srpm-macros
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.41% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

bugs.chromium.org https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=20450 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	7.5	AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness

CWE-416 Use After Free

References

codereview.qt-project.org /c/qt/qtbase/+/291706
patch, third-party-advisory
bugs.chromium.org /p/oss-fuzz/issues/detail?id=20450
exploit, issue-tracking, third-party-advisory
security.gentoo.org /glsa/202007-38
vendor-advisory, third-party-advisory

Sources

CVE List CVE-2020-12267
NVD CVE-2020-12267

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary