chrony: authentication doesn't protect symmetric associations against DoS attacks
Published Dec 9, 2019
6.5
MEDIUMCVSS 3.1
EPSS 1.70%
Description
chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service (inability to synchronize) via random timestamps in crafted NTP data packets.
Affected products
-
- Version before 1.31.1StatusaffectedConstraints-
- Version
No data.
Red Hat Enterprise Linux 7
chrony-0:2.1.1-1.el7
Fixed · RHSA-2015:2241
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 7 | chrony-0:2.1.1-1.el7 | Fixed | RHSA-2015:2241 |
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:L/UI:N/S:U/C:N/I:N/A:H
No CVSS v3.0 score for this CVE.
AV:N/AC:L/Au:S/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
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (14 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 1.70% (0.01696) | 76.31th | v5 (v2026.06.15) |
| Jun 15, 2026 | 1.70% (0.01696) | 74.08th | v5 (v2026.06.15) |
| Mar 30, 2025 | 0.71% (0.00707) | 69.86th | v4 (v2025.03.14) |
| Mar 29, 2025 | 2.32% (0.02320) | 74.63th | v4 (v2025.03.14) |
| Mar 17, 2025 | 0.71% (0.00707) | 70.49th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.14% (0.00142) | 51.44th | v3 (v2023.03.01) |
| Jun 21, 2024 | 0.14% (0.00142) | 50.16th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.14% (0.00142) | 48.14th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.05% (0.01055) | 52.13th | v2 (v2022.01.01) |
| Feb 13, 2023 | 1.05% (0.01055) | 51.58th | v2 (v2022.01.01) |
| Feb 3, 2023 | 0.95% (0.00950) | 31.66th | v2 (v2022.01.01) |
| Sep 17, 2022 | 1.05% (0.01055) | 50.47th | v2 (v2022.01.01) |
| Apr 1, 2022 | 1.05% (0.01055) | 48.43th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.05% (0.01055) | 27.52th | v2 (v2022.01.01) |
References (6)
- http://chrony.tuxfamily.org/News.html x_refsource_MISCRelease NotesVendor Advisory
- https://access.redhat.com/security/cve/CVE-2015-1853 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1209572 Issue Tracking
- https://nvd.nist.gov/vuln/detail/CVE-2015-1853
- https://security.gentoo.org/glsa/201507-01 x_refsource_MISCThird Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2015-1853
| Link | Providers | Tags |
|---|---|---|
| http://chrony.tuxfamily.org/News.html | x_refsource_MISCRelease NotesVendor Advisory | |
| https://access.redhat.com/security/cve/CVE-2015-1853 | Vendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=1209572 | Issue Tracking | |
| https://nvd.nist.gov/vuln/detail/CVE-2015-1853 | ||
| https://security.gentoo.org/glsa/201507-01 | x_refsource_MISCThird Party Advisory | |
| https://www.cve.org/CVERecord?id=CVE-2015-1853 |
Change history (0)
No recorded changes yet.