qt5-qtwebsockets: websocket implementation allows only limited size for frames and messages therefore attacker can cause DOS
Published Feb 28, 2020
7.5
HIGHCVSS 3.1
EPSS 2.34%
Description
In Qt through 5.14.1, the WebSocket implementation accepts up to 2GB for frames and 2GB for messages. Smaller limits cannot be configured. This makes it easier for attackers to cause a denial of service (memory consumption).
Affected products
No data.
No data.
Red Hat Enterprise Linux 8
qt5-qtbase-0:5.12.5-6.el8
Fixed · RHSA-2020:4690
Red Hat Enterprise Linux 8
qt5-qttools-0:5.12.5-2.el8
Fixed · RHSA-2020:4690
Red Hat Enterprise Linux 8
qt5-qtwebsockets-0:5.12.5-2.el8
Fixed · RHSA-2020:4690
Red Hat Enterprise Linux 7
qt5-qtwebsockets
Will not fix
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 8 | qt5-qtbase-0:5.12.5-6.el8 | Fixed | RHSA-2020:4690 |
| Red Hat Enterprise Linux 8 | qt5-qttools-0:5.12.5-2.el8 | Fixed | RHSA-2020:4690 |
| Red Hat Enterprise Linux 8 | qt5-qtwebsockets-0:5.12.5-2.el8 | Fixed | RHSA-2020:4690 |
| Red Hat Enterprise Linux 7 | qt5-qtwebsockets | Will not fix | n/a |
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
1 other source (MITRE) ▾
CVSS:3.0/AC:L/AV:N/A:H/C:N/I:N/PR:N/S:C/UI:N
AV:N/AC:L/Au:N/C:N/I:N/A:P
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2021–2026- EPSS v1
- EPSS v2
- EPSS v3
- EPSS v5
Percentile over time
- EPSS v1
- EPSS v2
- EPSS v3
- EPSS v5
Table of values (13 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 2.34% (0.02339) | 82.98th | v5 (v2026.06.15) |
| Jun 15, 2026 | 2.24% (0.02238) | 80.46th | v5 (v2026.06.15) |
| Jul 20, 2024 | 0.12% (0.00117) | 46.01th | v3 (v2023.03.01) |
| Jul 3, 2024 | 0.12% (0.00117) | 45.87th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.12% (0.00117) | 43.87th | v3 (v2023.03.01) |
| Mar 6, 2023 | 0.89% (0.00885) | 27.89th | v2 (v2022.01.01) |
| Sep 10, 2022 | 0.89% (0.00885) | 26.24th | v2 (v2022.01.01) |
| Apr 1, 2022 | 0.89% (0.00885) | 24.24th | v2 (v2022.01.01) |
| Feb 4, 2022 | 0.89% (0.00885) | 10.50th | v2 (v2022.01.01) |
| Feb 3, 2022 | 0.83% (0.00826) | 22.22th | v1 |
| Jan 6, 2022 | 0.83% (0.00826) | 21.62th | v1 |
| Sep 1, 2021 | 0.83% (0.00826) | 52.18th | v1 |
| Apr 14, 2021 | 0.83% (0.00826) | 0.00th | v1 |
References (6)
- https://access.redhat.com/security/cve/CVE-2018-21035 Vendor Advisory
- https://bugreports.qt.io/browse/QTBUG-70693 x_refsource_MISCExploitThird Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1810964 Issue Tracking
- https://codereview.qt-project.org/c/qt/qtwebsockets/+/284735 x_refsource_MISCPatchThird Party Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2018-21035
- https://www.cve.org/CVERecord?id=CVE-2018-21035
| Link | Providers | Tags |
|---|---|---|
| https://access.redhat.com/security/cve/CVE-2018-21035 | Vendor Advisory | |
| https://bugreports.qt.io/browse/QTBUG-70693 | x_refsource_MISCExploitThird Party Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=1810964 | Issue Tracking | |
| https://codereview.qt-project.org/c/qt/qtwebsockets/+/284735 | x_refsource_MISCPatchThird Party Advisory | |
| https://nvd.nist.gov/vuln/detail/CVE-2018-21035 | ||
| https://www.cve.org/CVERecord?id=CVE-2018-21035 |
Change history (0)
No recorded changes yet.