CVE-2015-3405

ntp-keygen in ntp 4.2.8px before 4.2.8p2-RC2 and 4.3.x before 4.3.12 does not generate MD5 keys with sufficient entropy on big endian machines when the lowest order byte of the temp variable is between 0x20 and 0x7f and not #, which might allow remote attackers to obtain the value of generated MD5 keys via a brute force attack with the 93 possible keys.

Published: 2017-08-09 Last update: 2026-05-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2015-3405 is rated High Risk (68.1/100): CVSS High severity, with high exploitation likelihood (EPSS 16.56%, 95th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +10.35% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2015-3405

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-28 6.21% 16.56% +10.35%
2 2025-12-27 16.56% 6.21% -10.35%
3 2025-12-15 — 16.56% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2015-3405

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.0 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2015-3405

OS Trackers for CVE-2015-3405

vendor priority summary link
debian not yet assigned CVE-2015-3405 not yet assigned priority: Debian including 1 source packages (ntp), 1 status rows across 1 suites (bullseye): resolved 1. https://security-tracker.debian.org/tracker/CVE-2015-3405
redhat low — https://access.redhat.com/security/cve/CVE-2015-3405
ubuntu medium CVE-2015-3405 medium priority: Ubuntu including 1 source packages (ntp), 6 status rows across 6 suites (lucid, precise, trusty, upstream, utopic, vivid): released 5, ignored 1. https://ubuntu.com/security/CVE-2015-3405

Affected software / configurations for CVE-2015-3405

Vendor Product Version Raw CPE
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p2-rc1:*:*:*:*:*:*
ntp ntp 4.3.0 cpe:2.3:a:ntp:ntp:4.3.0:*:*:*:*:*:*:*
ntp ntp 4.3.1 cpe:2.3:a:ntp:ntp:4.3.1:*:*:*:*:*:*:*
ntp ntp 4.3.2 cpe:2.3:a:ntp:ntp:4.3.2:*:*:*:*:*:*:*
ntp ntp 4.3.3 cpe:2.3:a:ntp:ntp:4.3.3:*:*:*:*:*:*:*
ntp ntp 4.3.4 cpe:2.3:a:ntp:ntp:4.3.4:*:*:*:*:*:*:*
ntp ntp 4.3.5 cpe:2.3:a:ntp:ntp:4.3.5:*:*:*:*:*:*:*
ntp ntp 4.3.6 cpe:2.3:a:ntp:ntp:4.3.6:*:*:*:*:*:*:*
ntp ntp 4.3.7 cpe:2.3:a:ntp:ntp:4.3.7:*:*:*:*:*:*:*
ntp ntp 4.3.8 cpe:2.3:a:ntp:ntp:4.3.8:*:*:*:*:*:*:*
ntp ntp 4.3.9 cpe:2.3:a:ntp:ntp:4.3.9:*:*:*:*:*:*:*
ntp ntp 4.3.10 cpe:2.3:a:ntp:ntp:4.3.10:*:*:*:*:*:*:*
ntp ntp 4.3.11 cpe:2.3:a:ntp:ntp:4.3.11:*:*:*:*:*:*:*
debian debian_linux 7.0 cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
opensuse suse_linux_enterprise_server 11.0 cpe:2.3:o:opensuse:suse_linux_enterprise_server:11.0:sp3:*:*:*:*:*:*
opensuse_project suse_linux_enterprise_desktop 11.0 cpe:2.3:o:opensuse_project:suse_linux_enterprise_desktop:11.0:sp3:*:*:*:*:*:*
suse suse_linux_enterprise_server 11.0 cpe:2.3:o:suse:suse_linux_enterprise_server:11.0:sp3:*:*:*:vmware:*:*
fedoraproject fedora 21 cpe:2.3:o:fedoraproject:fedora:21:*:*:*:*:*:*:*
redhat enterprise_linux_desktop 6.0 cpe:2.3:o:redhat:enterprise_linux_desktop:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_for_ibm_z_systems 6.0 cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_big_endian 6.0 cpe:2.3:o:redhat:enterprise_linux_for_power_big_endian:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_for_scientific_computing 6.0 cpe:2.3:o:redhat:enterprise_linux_for_scientific_computing:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_server 6.0 cpe:2.3:o:redhat:enterprise_linux_server:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_server_from_rhui_6 6.0 cpe:2.3:o:redhat:enterprise_linux_server_from_rhui_6:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_workstation 6.0 cpe:2.3:o:redhat:enterprise_linux_workstation:6.0:*:*:*:*:*:*:*

References for CVE-2015-3405

URL Tags
http://bk1.ntp.org/ntp-stable/?PAGE=patch&REV=55199296N2gFqH1Hm5GOnhrk9Ypygg Third Party Advisory Vendor Advisory
http://lists.fedoraproject.org/pipermail/package-announce/2015-April/156248.html Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00000.html Third Party Advisory
http://rhn.redhat.com/errata/RHSA-2015-1459.html Third Party Advisory VDB Entry
http://rhn.redhat.com/errata/RHSA-2015-2231.html Third Party Advisory VDB Entry
http://www.debian.org/security/2015/dsa-3223 Third Party Advisory
http://www.debian.org/security/2015/dsa-3388 Third Party Advisory
http://www.openwall.com/lists/oss-security/2015/04/23/14 Mailing List Third Party Advisory
http://www.oracle.com/technetwork/topics/security/bulletinapr2015-2511959.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
http://www.securityfocus.com/bid/74045 Third Party Advisory VDB Entry
https://bugs.ntp.org/show_bug.cgi?id=2797 Issue Tracking Third Party Advisory Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1210324 Issue Tracking Patch Third Party Advisory VDB Entry
https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf03886en_us
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