How severe is CVE-2015-1853?

CVE-2015-1853 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2015-1853 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-1853?

CVE-2015-1853 affects Tuxfamily Chrony. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2015-1853?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2015-1853 published?

CVE-2015-1853 was published on 2019-12-09 and last updated on 2026-06-17.

CVE-2015-1853

CVE-2015-1853 is a medium-severity vulnerability in Tuxfamily Chrony with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 2% (74th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Tuxfamily Chrony
Published: 2019-12-09
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2015-1853?: 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.
How severe is CVE-2015-1853?: CVE-2015-1853 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2015-1853 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-1853?: CVE-2015-1853 affects Tuxfamily Chrony. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2015-1853?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2015-1853 published?: CVE-2015-1853 was published on 2019-12-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:tuxfamily:chrony:*:*:*:*:*:*:*:*

More vulnerabilities in Tuxfamily Chrony

CVE-2016-1567 — High (CVSS 8.1): chrony before 1.31.2 and 2.x before 2.2.1 do not verify peer associations of symmetric keys when authenticating…
CVE-2015-1822 — Medium (CVSS 6.5): chrony before 1.31.1 does not initialize the last "next" pointer when saving unacknowledged replies to command…
CVE-2015-1821 — Medium (CVSS 6.5): Heap-based buffer overflow in chrony before 1.31.1 allows remote authenticated users to cause a denial of service…
CVE-2020-14367 — Medium (CVSS 6.0): A flaw was found in chrony versions before 3.5.1 when creating the PID file under the /var/run/chrony folder. The file…
CVE-2012-4503 — Medium (CVSS 5.0): cmdmon.c in Chrony before 1.29 allows remote attackers to obtain potentially sensitive information from stack memory…
CVE-2012-4502 — Medium (CVSS 5.0): Multiple integer overflows in pktlength.c in Chrony before 1.29 allow remote attackers to cause a denial of service…

All CVEs affecting Tuxfamily Chrony →