CVE-2015-7855Ntp Vulnerability
The decodenetnum 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 (assertion failure) via a 6 or mode 7 packet containing a long data value.
Published Aug 7, 2017 · Updated Aug 4, 2026 · Also known as DEBIAN-CVE-2015-7855, UBUNTU-CVE-2015-7855
Key Facts
Routine patching- CVE-2015-7855 is a medium-severity vulnerability (CVSS 6.5 v3.1) affecting Oncommand Balance (Netapp), Oncommand Performance Manager (Netapp), Oncommand Unified Manager (Netapp) and 13 more products.
- It is not listed in any known-exploited vulnerabilities catalog. A public exploit is reported by tracking sources, but no code link is listed yet.
- EPSS estimates a 31% probability of exploitation in the next 30 days.
- Fixed versions are available, including Ntp 1:4.2.6.p2+dfsg-1+deb6u4, Ntp 1:4.2.6.p5+dfsg-2+deb7u6, Ntp 1:4.2.6.p5+dfsg-3ubuntu2.14.04.5.
- Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.
Scores
CVSS v3.1
6.5
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS (30-day exploit likelihood)
31%
Higher than 98.2% of all scored CVEs
Exploit maturity
Proof of concept
ATLAS score
41/100
Publication score, see How it works
Exploitation Verdict
KEV listed
Not listed
Federal due date
None
No federal due date
Ransomware use
Not reported
Attributed actors
None named
Exploit & Defence Guidance
Exploit maturity
Proof of concept
Public exploit code
2
Proof-of-concept links
In-the-wild evidence
0
Reports of active use
Advisories And Exploit References
- advisoryhttps://security-tracker.debian.org/tracker/CVE-2015-7855
- advisoryhttps://ubuntu.com/security/CVE-2015-7855
- advisoryhttps://www.cve.org/CVERecord?id=CVE-2015-7855
- advisoryhttps://bugzilla.redhat.com/show_bug.cgi?id=1274264
- advisoryhttps://bugzilla.suse.com/782060
- advisoryhttps://bugzilla.suse.com/784760
Description
The decodenetnum 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 (assertion failure) via a 6 or mode 7 packet containing a long data value.
Affected Products
92 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Oncommand BalanceNetapp | See advisory | n/a |
| Oncommand Performance ManagerNetapp | See advisory | n/a |
| Oncommand Unified ManagerNetapp | See advisory | n/a |
| NtpNtp | 4.2.8, 4.2.8-p1, 4.2.8-p1-beta1, 4.2.8-p1-beta2, 4.2.8-p1-beta3, 4.2.8-p1-beta4, 4.2.8-p1-beta5, 4.2.8-p1-rc1 | 4.2.8 |
| Debian LinuxDebian | 7.0, 8.0, 9.0 | n/a |
Patched Releases
Ntp
1:4.2.6.p2+dfsg-1+deb6u4, 1:4.2.6.p5+dfsg-2+deb7u6, 1:4.2.6.p5+dfsg-3ubuntu2.14.04.5, 1:4.2.6.p5+dfsg-7+deb8u1, 1:4.2.8p4+dfsg-1, 4.2.8p4-5.1, 4.2.8p4-9.2, 4.2.8p6-41.1, 4.2.8p6-46.5.2, 4.2.8p7-25.15.1, 4.2.8p9-1.1, NA, 4.2.8
ntp-debuginfo
4.2.8p7-25.15.1
ntp-debugsource
4.2.8p7-25.15.1
ntp-doc
4.2.8p4-5.1, 4.2.8p4-9.2, 4.2.8p6-41.1, 4.2.8p6-46.5.2, 4.2.8p7-25.15.1, 4.2.8p9-1.1
ntp-perl
NA
ntpstat
NA
yast2-ntp-client
2.17.14.1-1.12.1, 3.1.12.4-8.2
yast2-ntp-client-devel-doc
3.1.12.4-8.2
Timeline
Publicly disclosed
Aug 7, 2017
Last updated
Aug 4, 2026
Weakness Type
- CWE-20 Improper Input Validation
References
- advisorysecurity-tracker.debian.org · CVE-2015-7855
- advisoryubuntu.com · CVE-2015-7855
- advisorycve.org · CVERecord
- advisorybugzilla.redhat.com · show_bug.cgi
- advisorybugzilla.suse.com · 782060
FAQ
Common Questions.
The decodenetnum 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 (assertion failure) via a 6 or mode 7 packet containing a long data value.
Affected: Oncommand Balance (Netapp); Oncommand Performance Manager (Netapp); Oncommand Unified Manager (Netapp), among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
A public exploit is reported by tracking sources, but no code link is listed yet.
Fixed versions are available, including Ntp 1:4.2.6.p2+dfsg-1+deb6u4, Ntp 1:4.2.6.p5+dfsg-2+deb7u6, Ntp 1:4.2.6.p5+dfsg-3ubuntu2.14.04.5.
Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.
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