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Fencer Intel
high 7.5

CVE-2015-7691 json

The crypto_xmit function in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service…

published 9y ago modified 4mo ago also EUVD-2015-7593

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
7.1%
EPSS 7.1% chance of exploitation in 30 days, percentile 94%
public exploits
0
none known

Summary

The crypto_xmit function in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (crash) via crafted packets containing particular autokey operations. NOTE: This vulnerability exists due to an incomplete fix for CVE-2014-9750.

Patch / fix

  • ntp ntp 4.2.8, 4.3.77
  • ntp Debian 11 1:4.2.8p4+dfsg-1

debian advisories DEBIAN-CVE-2015-7691

  • ntp Ubuntu 14.04 LTS 1:4.2.6.p5+dfsg-3ubuntu2.14.04.5

ubuntu advisories UBUNTU-CVE-2015-7691

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ntp RHEL 7 4.2.6p5-25.el7
  • sntp RHEL 7 4.2.6p5-25.el7
  • ntpdate RHEL 7 4.2.6p5-25.el7
  • ntp-perl RHEL 7 4.2.6p5-25.el7
  • ntp RHEL 6 4.2.6p5-10.el6
  • ntpdate RHEL 6 4.2.6p5-10.el6
  • ntp-perl RHEL 6 4.2.6p5-10.el6

red hat advisories RHSA-2016:2583RHSA-2016:0780

  • ntp SLES 11 SP3-TERADATA, SLES 11 SP3-LTSS, SLES 11 SP2-LTSS +3 more 4.2.8p6-41.1
  • ntp SLES for SAP 12, SLES 12, SLED 12 4.2.8p6-46.5.2
  • yast2-ntp-client SLES for SAP 12, SLES 12, SLED 12 +1 more 3.1.12.4-8.2
  • ntp SLES for SAP 11 SP4, SLES 11 SP4, SLED 11 SP4 4.2.8p4-5.1
  • yast2-ntp-client SLES 11 SP2-LTSS 2.17.14.1-1.12.1

suse advisories SUSE-SU-2016:1311-1SUSE-SU-2016:1247-1SUSE-SU-2015:2058-1

  • ntp openSUSE Tumbleweed 4.2.8p9-1.1

opensuse advisories openSUSE-SU-2024:10181-1

Is CVE-2015-7691 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2015-7691 updated cvss 4.0

ntp: incomplete checks in ntp_crypto.c

  • Red Hat Enterprise Linux 5 ntp
    affected: workaround, no fix planned “Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.”
  • Red Hat Enterprise Linux Client (v. 7) ntp 4.2.6p5-25.el7, ntpdate 4.2.6p5-25.el7 Red Hat Enterprise Linux Client Optional (v. 7) sntp 4.2.6p5-25.el7, ntp-perl 4.2.6p5-25.el7 Red Hat Enterprise Linux ComputeNode (v. 7) ntp 4.2.6p5-25.el7, ntpdate 4.2.6p5-25.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) sntp 4.2.6p5-25.el7, ntp-perl 4.2.6p5-25.el7
    fixed: vendor fix “Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.” RHSA-2016:2583
  • Red Hat Enterprise Linux Desktop (v. 6) ntp 4.2.6p5-10.el6, ntpdate 4.2.6p5-10.el6 Red Hat Enterprise Linux Desktop Optional (v. 6) ntp-perl 4.2.6p5-10.el6 Red Hat Enterprise Linux HPC Node (v. 6) ntp 4.2.6p5-10.el6, ntpdate 4.2.6p5-10.el6 Red Hat Enterprise Linux HPC Node Optional (v. 6) ntp-perl 4.2.6p5-10.el6 Red Hat Enterprise Linux Server (v. 6) ntp 4.2.6p5-10.el6, ntpdate 4.2.6p5-10.el6
    fixed: vendor fix “Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.” RHSA-2016:0780
  • Red Hat Enterprise Linux Server (v. 7) ntp 4.2.6p5-25.el7, ntpdate 4.2.6p5-25.el7
    fixed: vendor fix “Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.” RHSA-2016:2583
  • Red Hat Enterprise Linux Server Optional (v. 6) ntp-perl 4.2.6p5-10.el6
    fixed: vendor fix “Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.” RHSA-2016:0780
  • Red Hat Enterprise Linux Server Optional (v. 7) sntp 4.2.6p5-25.el7, ntp-perl 4.2.6p5-25.el7
    fixed: vendor fix “Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.” RHSA-2016:2583
  • Red Hat Enterprise Linux Workstation (v. 6) ntp 4.2.6p5-10.el6, ntpdate 4.2.6p5-10.el6
    fixed: vendor fix “Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.” RHSA-2016:0780
  • Red Hat Enterprise Linux Workstation (v. 7) ntp 4.2.6p5-25.el7, ntpdate 4.2.6p5-25.el7
    fixed: vendor fix “Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.” RHSA-2016:2583
show 2 more
  • Red Hat Enterprise Linux Workstation Optional (v. 6) ntp-perl 4.2.6p5-10.el6
    fixed: vendor fix “Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.” RHSA-2016:0780
  • Red Hat Enterprise Linux Workstation Optional (v. 7) sntp 4.2.6p5-25.el7, ntp-perl 4.2.6p5-25.el7
    fixed: vendor fix “Disable NTP autokey authentication by removing, or commenting out, all configuration directives beginning with the 'crypto' keyword in your ntp.conf file.” RHSA-2016:2583

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

Exploit prediction

7.10% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Intel 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.