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Fencer Vulns
medium 5.6

CVE-2023-26554 json

mstolfp in libntp/mstolfp.c in NTP 4.2.8p15 has an out-of-bounds write when adding a '\0' character.

published 2023-04-11 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-30351

cvss
5.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

mstolfp in libntp/mstolfp.c in NTP 4.2.8p15 has an out-of-bounds write when adding a '\0' character. An adversary may be able to attack a client ntpq process, but cannot attack ntpd.

Patch / fix

  • ntp SLES for SAP 12 SP5, SLES 12 SP5 4.2.8p15-100.1
  • ntp SLE Module for Legacy 15 SP4, openSUSE Leap 15.4 4.2.8p15-150000.4.22.1

suse advisories SUSE-SU-2023:2171-1SUSE-SU-2023:2142-1

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-2023-26554 updated cvss 5.6

ntp: an out-of-bounds write when adding a '\0' character

  • Red Hat Enterprise Linux 6 ntp, ntpdate, ntp-perl
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 ntp, sntp, ntpdate, ntp-perl
    affected: no fix planned “Will not fix”

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

cisa ICSA-24-165-05 updated cvss 5.6

Siemens SITOP UPS1600

  • Siemens SITOP UPS1600 10 A Ethernet/ PROFINET (6EP4134-3AB00-2AY0) <V2.5.4 Siemens SITOP UPS1600 20 A Ethernet/ PROFINET (6EP4136-3AB00-2AY0) <V2.5.4 Siemens SITOP UPS1600 40 A Ethernet/ PROFINET (6EP4137-3AB00-2AY0) <V2.5.4 Siemens SITOP UPS1600 EX 20 A Ethernet PROFINET (6EP4136-3AC00-2AY0) <V2.5.4
    affected: fixed in V2.5.4 support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
20 mo ago

Exploit prediction

0.64% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
NVD 3.1 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
CNA 3.1 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Classification

Weakness

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.