ntp: ASSERT in decodenetnum() on invalid values
Published Aug 7, 2017
6.5
MEDIUMCVSS 3.1
EPSS 31.07%
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
No data.
Configuration 1
- ≥ 4.2.0 · < 4.2.8
- ≥ 4.3.0 · < 4.3.77
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
Configuration 2
- 7.0
- 8.0
- 9.0
Configuration 3
- n/a
- n/a
- n/a
- n/a
- n/a
Configuration 4
- n/a
Configuration 5
- n/a
Running on/with
- n/a
No data.
Red Hat Enterprise Linux 5
ntp
Not affected
Red Hat Enterprise Linux 6
ntp
Not affected
Red Hat Enterprise Linux 7
ntp
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 5 | ntp | Not affected | n/a |
| Red Hat Enterprise Linux 6 | ntp | Not affected | n/a |
| Red Hat Enterprise Linux 7 | ntp | Not affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
This issue did not affect the versions of ntp as shipped with Red Hat Enterprise Linux 5, 6, and 7 as they do not include support for the mrulist feature, which exposes the decodenetnum() function.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
No CVSS v3.0 score for this CVE.
AV:N/AC:L/Au:S/C:N/I:N/A:P
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (20 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 31.07% (0.31068) | 98.22th | v5 (v2026.06.15) |
| Jun 15, 2026 | 31.07% (0.31068) | 98.03th | v5 (v2026.06.15) |
| May 21, 2026 | 50.07% (0.50067) | 97.86th | v4 (v2025.03.14) |
| May 1, 2026 | 65.70% (0.65699) | 98.52th | v4 (v2025.03.14) |
| Dec 28, 2025 | 60.12% (0.60116) | 98.18th | v4 (v2025.03.14) |
| Dec 27, 2025 | 63.46% (0.63461) | 98.34th | v4 (v2025.03.14) |
| Dec 14, 2025 | 60.12% (0.60116) | 98.17th | v4 (v2025.03.14) |
| Dec 13, 2025 | 67.69% (0.67693) | 98.51th | v4 (v2025.03.14) |
| Oct 13, 2025 | 63.46% (0.63461) | 98.30th | v4 (v2025.03.14) |
| Aug 10, 2025 | 60.88% (0.60881) | 98.22th | v4 (v2025.03.14) |
| Mar 30, 2025 | 48.41% (0.48405) | 97.50th | v4 (v2025.03.14) |
| Mar 29, 2025 | 52.33% (0.52331) | 96.97th | v4 (v2025.03.14) |
| Mar 17, 2025 | 48.41% (0.48405) | 97.46th | v4 (v2025.03.14) |
| Dec 17, 2024 | 94.42% (0.94420) | 99.41th | v3 (v2023.03.01) |
| Dec 12, 2024 | 96.94% (0.96943) | 99.78th | v3 (v2023.03.01) |
| Apr 23, 2023 | 97.07% (0.97069) | 99.60th | v3 (v2023.03.01) |
| Mar 7, 2023 | 97.05% (0.97049) | 99.55th | v3 (v2023.03.01) |
| Mar 6, 2023 | 17.73% (0.17731) | 96.25th | v2 (v2022.01.01) |
| Apr 1, 2022 | 17.73% (0.17731) | 95.92th | v2 (v2022.01.01) |
| Feb 4, 2022 | 17.73% (0.17731) | 93.35th | v2 (v2022.01.01) |
References (16)
- http://support.ntp.org/bin/view/Main/NtpBug2922 x_refsource_CONFIRMPatchVendor Advisory
- http://support.ntp.org/bin/view/Main/SecurityNotice#October_2015_NTP_Security_Vulner
- http://www.debian.org/security/2015/dsa-3388 vendor-advisoryx_refsource_DEBIANThird Party Advisory
- http://www.securityfocus.com/bid/77283 vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry
- http://www.securitytracker.com/id/1033951 vdb-entryx_refsource_SECTRACKThird Party AdvisoryVDB Entry
- https://access.redhat.com/security/cve/CVE-2015-7855 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1274264 x_refsource_CONFIRMIssue TrackingThird Party AdvisoryVDB Entry
- https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf x_refsource_CONFIRMThird Party Advisory
- https://github.com/ntp-project/ntp/blob/stable/NEWS#L295
- https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05270839 x_refsource_CONFIRMThird Party AdvisoryVDB Entry
- https://nvd.nist.gov/vuln/detail/CVE-2015-7855
- https://security.gentoo.org/glsa/201607-15 vendor-advisoryx_refsource_GENTOOThird Party AdvisoryVDB Entry
- https://security.netapp.com/advisory/ntap-20171004-0001/ x_refsource_CONFIRMThird Party Advisory
- https://us-cert.cisa.gov/ics/advisories/icsa-21-103-11 x_refsource_CONFIRMThird Party AdvisoryUS Government Resource
- https://www.cve.org/CVERecord?id=CVE-2015-7855
- https://www.exploit-db.com/exploits/40840/ exploitx_refsource_EXPLOIT-DBThird Party AdvisoryVDB Entry
Change history (0)
No recorded changes yet.