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Fencer Vulns
high 7.5

CVE-2020-13962 json

Qt 5.12.2 through 5.14.2, as used in unofficial builds of Mumble 1.3.0 and other products, mishandles OpenSSL's error queue, which can caus…

published 2020-06-08 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-6136

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.9%
EPSS 2.9% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

Qt 5.12.2 through 5.14.2, as used in unofficial builds of Mumble 1.3.0 and other products, mishandles OpenSSL's error queue, which can cause a denial of service to QSslSocket users. Because errors leak in unrelated TLS sessions, an unrelated session may be disconnected when any handshake fails. (Mumble 1.3.1 is not affected, regardless of the Qt version.)

Patch / fix

  • qt qt 5.12.9
  • qtbase-opensource-src Debian 14, Debian 13, Debian 12 5.14.2+dfsg-6

debian advisories DEBIAN-CVE-2020-13962

  • qtbase-opensource-src Ubuntu Pro 20.04 LTS 5.12.8+dfsg-0ubuntu2.1+esm3

ubuntu advisories UBUNTU-CVE-2020-13962

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • qt5-qtbase RHEL 8 5.12.5-6.el8
  • qt5-qtwebsockets RHEL 8 5.12.5-2.el8
  • qt5-qttools RHEL 8 5.12.5-2.el8
  • qt5-designer RHEL 8 5.12.5-2.el8
  • qt5-doctools RHEL 8 5.12.5-2.el8
  • qt5-linguist RHEL 8 5.12.5-2.el8
  • qt5-assistant RHEL 8 5.12.5-2.el8
  • qt5-qtbase-gui RHEL 8 5.12.5-6.el8

red hat advisories RHSA-2020:4690

  • libqt5-qtbase SLE Module for Desktop Applications 15 SP2, SLE Module for Basesystem 15 SP2 5.12.7-4.3.1

suse advisories SUSE-SU-2020:2357-1

  • libqt5-qtbase openSUSE Tumbleweed 5.15.2+kde268-2.1
  • libqt5-qtbase openSUSE Leap 15.2 5.12.7-lp152.3.3.1

opensuse advisories openSUSE-SU-2024:11742-1openSUSE-SU-2020:1319-1

  • qt5-qtwebsockets Rocky Linux 8 5.12.5-2.el8

rocky linux advisories RLSA-2020:4690

  • qt5-qtsvg CBL-Mariner 2.0 5.12.11-3

azure linux advisories AZL-6835

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2020-13962 updated cvss 7.5

qt5: incorrectly calls SSL_shutdown() in OpenSSL mid-handshake causing denial of service in TLS applications

  • Red Hat CodeReady Linux Builder (v. 8) qt5-qtbase-static 5.12.5-6.el8, qt5-qttools-static 5.12.5-2.el8, qt5-qtbase-debuginfo 5.12.5-6.el8, qt5-qttools-debuginfo 5.12.5-2.el8, qt5-designer-debuginfo 5.12.5-2.el8, qt5-doctools-debuginfo 5.12.5-2.el8, +18 more Red Hat Enterprise Linux AppStream (v. 8) qt5-qtbase 5.12.5-6.el8, qt5-qttools 5.12.5-2.el8, qt5-designer 5.12.5-2.el8, qt5-doctools 5.12.5-2.el8, qt5-linguist 5.12.5-2.el8, qt5-assistant 5.12.5-2.el8, +14 more
    fixed: vendor fix RHSA-2020:4690

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

2.86% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/mumble-voip/mumble/issues/3679 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

References

Sources

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.