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CVE-2015-7855

43
FAUCET Score

CVE-2015-7855 is a denial-of-service vulnerability in the decodenetnum function of NTP versions 4.2.x before 4.2.8p4 and 4.3.x before 4.3.77, affecting products from vendors like Debian, NetApp, and Siemens. With a CVSS score of 6.5 (Medium), it can be exploited remotely with low attack complexity, leading to a high availability impact (assertion failure). While not listed on CISA's KEV catalog, an ExploitDB entry exists (EDB-40840), and it has garnered significant community discussion and media coverage, indicating awareness and potential for exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
>= 4.2.0, < 4.2.8CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:*:*:*:*:*:*:*:*
>= 4.3.0, < 4.3.77CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:*:*:*:*:*:*:*:*
4.2.8CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.2.8:-:*:*:*:*:*:*
4.2.8CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.2.8:p1:*:*:*:*:*:*
4.2.8CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.2.8:p1-beta1:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
31.07%
Probability of exploitation in next 30 days
EPSS Percentile
98.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
ExploitDB: EDB-40840 · Nov 28, 2016
This CVE's current EPSS score of 0.3107 is in the 99th percentile among its peer group of 21,939 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Advisories (1)

redhatCVE-2015-7855Low

ntp: ASSERT in decodenetnum() on invalid values

Oct 21, 2015

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingThird Party AdvisoryVDB Entry
cert-portal.siemens.com / productcert/pdf/ssa-497656.pdf
Third Party Advisory
h20566.www2.hpe.com / portal/site/hpsc/public/kb/docDisplay
Third Party AdvisoryVDB Entry
security.gentoo.org / glsa/201607-15
Third Party AdvisoryVDB Entry
security.netapp.com / advisory/ntap-20171004-0001
Third Party Advisory
support.ntp.org / bin/view/Main/NtpBug2922
PatchVendor Advisory
us-cert.cisa.gov / ics/advisories/icsa-21-103-11
Third Party AdvisoryUS Government Resource
exploit-db.com / exploits/40840
ExploitThird Party AdvisoryVDB Entry
debian.org / security/2015/dsa-3388
Third Party Advisory
securityfocus.com / bid/77283
Third Party AdvisoryVDB Entry
securitytracker.com / id/1033951
Third Party AdvisoryVDB Entry