CVE-2016-1551

lowpriority · track · 16EPSS 0.022 · 83 %ileDEEUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
2.23% (83rd) EPSS
CVSS 2.6 · low
Is it mine?
8 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · auma_psirt · nvd

EPSS · scored 2026-10-27

ntpd in NTP 4.2.8p3 and NTPsec a5fb34b9cc89b92a8fef2f459004865c93bb7f92 relies on the underlying operating system to protect it from requests that impersonate reference clocks. Because reference clocks are treated like other peers and stored in the same structure, any packet with a source ip address of a reference clock (127.127.1.1 for example) that reaches the receive() function will match that reference clock's peer record and will be treated as a trusted peer. Any system that lacks the typical martian packet filtering which would block these packets is in danger of having its time controlled by an attacker.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

  • FixedSIMA² Master Stationauma_psirt

    Upgrade your SIMA2 to software version 2.6 or above. The NTP service of the SIMA2 Master Station with software version V2.6 and above includes a current, supported version of ntpd.

  • MitigationSIMA² Master Stationauma_psirt

    1. If your SIMA2 does not need to provide time information to other systems or synchronize itself with an NTP server, disable the NTP client on those systems. Please note that the NTP client is disabled by default in SIMA2 2. In case you must use the NTP server on an SIMA2, choose from the following options to reduce NTP-based risks: - Allow NTP traffic to/from trusted NTP clients only - Monitor the network for malicious NTP traffic going to/coming from the SIMA2 - Filter malicious NTP traffic going to/coming from the SIMA2 Monitor NTP server operations on your SIMA2 (server availability, correctness of advertised time, NTP-related log entries, etc.) 3. In case you must use the NTP client on an SIMA2, choose from the following options to reduce NTP-based risks: - Use trusted NTP servers only - Allow NTP traffic to/from trusted NTP servers only - Monitor the network for malicious NTP traffic targeting the SIMA2 - Filter malicious NTP traffic targeting the SIMA2 - Monitor NTP client operations on your SIMA2 (correctness of system time, NTP-related log entries, etc.)

02

cvss

Technical severity, 0–10. One row per scoring source.

3.7
010

base score 0–10 · higher = more severe · hover a vector to decode

v2.02.6lowAV:N/AC:H/Au:N/C:N/I:P/A:Nprimary · NVD / NIST USexploitability 4.9 · impact 2.9
v3.03.7lowCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:Nprimary · NVD / NIST USexploitability 2.2 · impact 1.4
v3.03.4lowCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)
v3.03.7lowCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:Nsecondary · AUMA PSIRT
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-254USprimary
04

affected products (8)

Products and version ranges known to be affected.

05

advisories (1)

Vendor and ecosystem advisories describing this.

  • VDE-2022-032AUMA: Multiple Vulnerabilities in Automation Runtime NTP Service2022-08-09csaf · auma_psirtDE

    The SIMA2 Master Station features an NTP service based on ntpd, a reference implementation of the Network Time Protocol (NTP). Affected SIMA2 Master Stations with software version < V2.6 include an outdated version of ntpd which is affected by a large number of vulnerabilities

06

also known as (3)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

cnnvdenisa_euvdauma_psirtnvdNVDCVE.orgMITRE
published 2017-01-27modified 2026-06-17
09

references (19)

External citations — patches, advisories, analysis.

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