HOMEVULNERABILITIESCVE-2015-7855
MEDIUMPOC

CVE-2015-7855

CWE-20Published: August 7, 2017· Updated: Jun 17, 2026

6.5
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2015-7855 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.

A proof-of-concept (PoC) exploit exists for CVE-2015-7855. While not yet confirmed in active campaigns, the availability of PoC code increases exploitation risk substantially.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

Debian1 product(s)
debian linux
netapp5 product(s)
oncommand balanceoncommand performance manageroncommand unified managerclustered data ontapdata ontap
ntp1 product(s)
ntp
siemens4 product(s)
tim 4r-ie firmwaretim 4r-ietim 4r-ie dnp3 firmwaretim 4r-ie dnp3
Source: NVD CPE · 14 total CPE entries

Exploit & PoC Resources

POC AVAILABLEProof-of-concept code exists
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttp://support.ntp.org/bin/view/Main/NtpBug2922
PATCHhttp://support.ntp.org/bin/view/Main/NtpBug2922
ADVISORYhttp://www.debian.org/security/2015/dsa-3388
ADVISORYhttp://www.securityfocus.com/bid/77283
ADVISORYhttp://www.securitytracker.com/id/1033951
ADVISORYhttps://bugzilla.redhat.com/show_bug.cgi?id=1274264
ADVISORYhttps://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf
ADVISORYhttps://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05270839
ADVISORYhttps://security.gentoo.org/glsa/201607-15
ADVISORYhttps://security.netapp.com/advisory/ntap-20171004-0001/
ADVISORYhttps://us-cert.cisa.gov/ics/advisories/icsa-21-103-11
ADVISORYhttps://www.exploit-db.com/exploits/40840/
ADVISORYhttp://www.debian.org/security/2015/dsa-3388
ADVISORYhttp://www.securityfocus.com/bid/77283
ADVISORYhttp://www.securitytracker.com/id/1033951
ADVISORYhttps://bugzilla.redhat.com/show_bug.cgi?id=1274264
ADVISORYhttps://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf
ADVISORYhttps://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05270839
ADVISORYhttps://security.gentoo.org/glsa/201607-15
ADVISORYhttps://security.netapp.com/advisory/ntap-20171004-0001/
ADVISORYhttps://us-cert.cisa.gov/ics/advisories/icsa-21-103-11
ADVISORYhttps://www.exploit-db.com/exploits/40840/

All References (22)

→
http://support.ntp.org/bin/view/Main/NtpBug2922Patch · Vendor Advisory
→
http://www.debian.org/security/2015/dsa-3388Third Party Advisory
→
http://www.securityfocus.com/bid/77283Third Party Advisory · VDB Entry
→
http://www.securitytracker.com/id/1033951Third Party Advisory · VDB Entry
→
https://bugzilla.redhat.com/show_bug.cgi?id=1274264Issue Tracking · Third Party Advisory · VDB Entry
→
https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdfThird Party Advisory
→
https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05270839Third Party Advisory · VDB Entry
→
https://security.gentoo.org/glsa/201607-15Third Party Advisory · VDB Entry
→
https://security.netapp.com/advisory/ntap-20171004-0001/Third Party Advisory
→
https://us-cert.cisa.gov/ics/advisories/icsa-21-103-11Third Party Advisory · US Government Resource
→
https://www.exploit-db.com/exploits/40840/Exploit · Third Party Advisory · VDB Entry
→
http://support.ntp.org/bin/view/Main/NtpBug2922Patch · Vendor Advisory
→
http://www.debian.org/security/2015/dsa-3388Third Party Advisory
→
http://www.securityfocus.com/bid/77283Third Party Advisory · VDB Entry
→
http://www.securitytracker.com/id/1033951Third Party Advisory · VDB Entry

Quick Facts

CVE IDCVE-2015-7855
CVSS Score6.5 / 10
SeverityMEDIUM
WeaknessCWE-20
CISA KEVNo
ExploitPOC
Affected4 vendor(s)
PublishedAug 7, 2017

Related CVEs (CWE-20)

CVE-2021-21321
10.0
CVE-2007-6494
10.0
CVE-2020-12388
10.0
CVE-2020-12389
10.0
CVE-2023-41917
10.0
CVE-2008-6826
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2015-7855 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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