Description
The monlist feature in ntp_request.c in ntpd in NTP before 4.2.7p26 allows remote attackers to cause a denial of service (traffic amplification) via forged (1) REQ_MON_GETLIST or (2) REQ_MON_GETLIST_1 requests, as exploited in the wild in December 2013.
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 | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | ntp | 4.2.8p9-1.1 | openSUSE-SU-2024:10181-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | ntp +4 | 4.2.8p15-3.amzn2.0.4 | ALAS2-2021-1706 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | ntp +4 | 4.2.6p5-22.0.1.el7_2.2 | ELSA-2016-3612 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Metasploit 10 modules
-
SSDP ssdp:all M-SEARCH Amplification Scanner
auxiliary/scanner/upnp/ssdp_amp
-
NTP Monitor List Scanner
auxiliary/scanner/ntp/ntp_monlist
-
NTP Clock Variables Disclosure
auxiliary/scanner/ntp/ntp_readvar
-
NTP Mode 7 GET_RESTRICT DRDoS Scanner
auxiliary/scanner/ntp/ntp_reslist_dos
-
Portmapper Amplification Scanner
auxiliary/scanner/portmap/portmap_amp
-
NTP Mode 7 PEER_LIST DoS Scanner
auxiliary/scanner/ntp/ntp_peer_list_dos
-
NTP Mode 6 REQ_NONCE DRDoS Scanner
auxiliary/scanner/ntp/ntp_req_nonce_dos
-
NTP Mode 6 UNSETTRAP DRDoS Scanner
auxiliary/scanner/ntp/ntp_unsettrap_dos
-
UDP Amplification Scanner
auxiliary/scanner/udp/udp_amplification
-
NTP Mode 7 PEER_LIST_SUM DoS Scanner
auxiliary/scanner/ntp/ntp_peer_list_sum_dos
Exploit-DB 1
- NTP ntpd monlist Query Reflection - Denial of Service EDB-33073 · dos · Apr 28, 2014
GitHub 5 repositories
-
dani87/ntpscanner ★ 15 · Sep 7, 2014
Scans NTP servers for CVE-2013-5211 NTP DDOS amplification vulnerability.
-
sepehrdaddev/ntpdos ★ 10 · Sep 24, 2019
PoC for distributed NTP reflection DoS (CVE-2013-5211)
-
0xhav0c/CVE-2013-5211 ★ 6 · May 3, 2023
-
suedadam/ntpscanner ★ 2 · Dec 14, 2014
NTP monlist scanner CVE-2013-5211
-
requiempentest/NTP_CVE-2013-5211 ★ 0 · Oct 16, 2024
Exploit and check CVE-2013-5211
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 6
- openSUSE-SU-2024:10181-1 ntp-4.2.8p9-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- ICSA-14-051-04 NTP Reflection Attack CISA ICS & IT advisories · Jun 9, 2025
- ICSA-24-352-02 Hitachi Energy TropOS Devices Series 1400/2400/6400 CISA ICS & IT advisories · Dec 17, 2024
- VDE-2022-032 AUMA: Multiple Vulnerabilities in Automation Runtime NTP Service CERT@VDE · Aug 9, 2022
- ALAS2-2021-1706 Moderate: ntp security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Sep 15, 2021
- ELSA-2016-3612 Important: ntp security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Sep 9, 2016
References
- 59288 third-party-advisory
- https://h20564.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c04790232
- openSUSE-SU-2014:1149 vendor-advisory
- http://www.oracle.com/technetwork/topics/security/linuxbulletinjul2016-3090544.html
- HPSBUX02960 vendor-advisory
- TA14-013A third-party-advisory
- 64692 vdb-entry
- VU#348126 third-party-advisory
- HPSBOV03505 vendor-advisory
- [oss-security] 20131230 CVE to the ntp monlist DDoS issue? mailing-list
- 59726 third-party-advisory
- 1030433 vdb-entry
- http://www.eecis.udel.edu/~ntp/ntp_spool/ntp4/ntp-dev/ntp-dev-4.2.7p26.tar.gz
- http://ics-cert.us-cert.gov/advisories/ICSA-14-051-04
- http://aix.software.ibm.com/aix/efixes/security/ntp_advisory.asc
- http://www-947.ibm.com/support/entry/portal/docdisplay?lndocid=MIGR-5095861
- [pool] 20111210 Odd surge in traffic today mailing-list
- [oss-security] 20131230 Re: CVE to the ntp monlist DDoS issue? mailing-list
- http://www-947.ibm.com/support/entry/portal/docdisplay?lndocid=MIGR-5095892
- http://bugs.ntp.org/show_bug.cgi?id=1532
- https://puppet.com/security/cve/puppetlabs-ntp-nov-2015-advisory