Description
The ULOGTOD function in ntp.d in SNTP before 4.2.7p366 does not properly perform type conversions from a precision value to a double, which allows remote attackers to cause a denial of service (infinite loop) via a crafted NTP packet.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 11 | ntp | 1:4.2.8p3+dfsg-1 | — |
| Debian 8 | ntp | 1:4.2.6.p5+dfsg-7+deb8u1 | DSA-3388-1 |
| Debian 7 | ntp | 1:4.2.6.p5+dfsg-2+deb7u6 | DSA-3388-1 |
| Debian 6.0 | ntp | 1:4.2.6.p2+dfsg-1+deb6u4 | DLA-335-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 14.04 LTS | ntp | 1:4.2.6.p5+dfsg-3ubuntu2.14.04.5 | USN-2783-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7 | ntp +4 | 4.2.6p5-25.el7 | RHSA-2016:2583 |
| RHEL 6 | ntp +3 | 4.2.6p5-10.el6 | RHSA-2016:0780 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP2 | ntp | 4.2.8p9-55.1 | SUSE-SU-2016:3195-1 |
| SLES 12 SP1 | ntp | 4.2.8p9-55.1 | SUSE-SU-2016:3195-1 |
| SLES 12 | ntp | 4.2.8p9-46.18.1 | SUSE-SU-2016:3196-1 |
| SLES 11 SP4 | ntp | 4.2.8p9-57.2 | SUSE-SU-2016:3193-1 |
| SLES 11 SP3 | ntp | 4.2.8p6-41.1 | SUSE-SU-2017:0255-1, SUSE-SU-2016:1311-1 |
Show 9 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 11 SP2 | ntp | 4.2.8p6-41.1 | SUSE-SU-2017:0255-1, SUSE-SU-2016:1311-1 |
| SLES 11 SP2 | yast2-ntp-client | 2.17.14.1-1.12.1 | SUSE-SU-2016:1311-1 |
| SLES for SAP 12 SP2 | ntp | 4.2.8p9-55.1 | SUSE-SU-2016:3195-1 |
| SLES for SAP 12 SP1 | ntp | 4.2.8p9-55.1 | SUSE-SU-2016:3195-1 |
| SLES for SAP 12 | ntp | 4.2.8p9-46.18.1 | SUSE-SU-2016:3196-1 |
| SLES for SAP 11 SP4 | ntp | 4.2.8p9-57.2 | SUSE-SU-2016:3193-1 |
| SUSE OpenStack Cloud 5 | ntp | 4.2.8p6-41.1 | SUSE-SU-2017:0255-1, SUSE-SU-2016:1311-1 |
| SUSE Manager Proxy 2.1 | ntp | 4.2.8p6-41.1 | SUSE-SU-2017:0255-1, SUSE-SU-2016:1311-1 |
| SUSE Manager 2.1 | ntp | 4.2.8p6-41.1 | SUSE-SU-2017:0255-1, SUSE-SU-2016:1311-1 |
| SUSE Linux Enterprise Point of Sale 11 SP3 | ntp | 4.2.8p9-48.9.1 | SUSE-SU-2017:0255-1 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | ntp +4 | 4.2.6p5-25.0.1.el7 | ELSA-2016-2583 |
Advisories 13
- RHSA-2016:2583 Red Hat Security Advisory: ntp security and bug fix update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- RHSA-2016:0780 Red Hat Security Advisory: ntp security and bug fix update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- DLA-335-1 ntp - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3388-1 ntp - security update Debian Security (DSA / DLA) · Mar 9, 2026
- USN-2783-1 ntp vulnerabilities Ubuntu Security Notices (USN) · Feb 10, 2026
- SUSE-SU-2016:1311-1 Security update for ntp SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2016:3193-1 Security update for ntp SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2016:3195-1 Security update for ntp SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:0255-1 Security update for ntp SUSE / openSUSE Security Updates · Feb 4, 2026
- ICSA-21-103-11 Siemens TIM 4R-IE Devices CISA ICS & IT advisories · Jun 10, 2025
- SSA-497656 SSA-497656: Multiple NTP Vulnerabilities in TIM 4R-IE Devices Siemens ProductCERT · Jun 10, 2025
- SUSE-SU-2016:3196-1 Security update for ntp SUSE / openSUSE Security Updates · May 2, 2025
- ELSA-2016-2583 Moderate: ntp security and bug fix update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Nov 9, 2016
References
- http://aix.software.ibm.com/aix/efixes/security/ntp_advisory4.asc
- https://www-01.ibm.com/support/docview.wss?uid=isg3T1024157
- https://github.com/ntp-project/ntp/commit/5f295cd05c3c136d39f5b3e500a2d781bdbb59c8
- openSUSE-SU:2016:3280 vendor-advisory
- https://www.ibm.com/support/home/docdisplay?lndocid=migr-5099409
- http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
- USN-2783-1 vendor-advisory
- https://www-01.ibm.com/support/docview.wss?uid=swg21986956
- https://www-01.ibm.com/support/docview.wss?uid=swg21988706
- RHSA-2016:2583 vendor-advisory
- FEDORA-2015-77bfbc1bcd vendor-advisory
- http://bk1.ntp.org/ntp-dev/?PAGE=patch&REV=51786731Gr4-NOrTBC_a_uXO4wuGhg
- RHSA-2016:0780 vendor-advisory
- DSA-3388 vendor-advisory
- [oss-security] 20150825 Several low impact ntp.org ntpd issues mailing-list
- https://bugzilla.redhat.com/show_bug.cgi?id=1255118
- 76473 vdb-entry
- SUSE-SU:2016:1311 vendor-advisory
- FEDORA-2015-14212 vendor-advisory
- https://www-01.ibm.com/support/docview.wss?uid=swg21989542
- https://www-01.ibm.com/support/docview.wss?uid=swg21985122
- FEDORA-2015-14213 vendor-advisory
- https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf
- https://us-cert.cisa.gov/ics/advisories/icsa-21-103-11