CVE-2015-7853

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-13. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 12%CVSS: 9.8Exploit: Elevated riskExposed: 0

A fix is available — apply it.

The datalen parameter in the refclock driver in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to execute arbitrary code or cause a denial of service (crash) via a negative input value.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
65(Track*)
EG Risk 65/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation40% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
12%
EPSS %ILE
96%
KEV
Not listed

Published

August 7, 2017

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Aug 25, 2026
No patch confirmed yet.
generic

Multiple Vulnerabilities in ntpd Affecting Cisco Products - October 2015

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151021-ntp
generic

Locked Out | Packet Storm

http://packetstormsecurity.com/files/134137/Slackware-Security-Advisory-ntp-Updates.html
generic

Locked Out | Packet Storm

http://packetstormsecurity.com/files/134082/FreeBSD-Security-Advisory-ntp-Authentication-Bypass.html

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuntp (1:4.2.6.p5+dfsg-3ubuntu6.2) @ vivid2026-05-20ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
ntp—1:4.2.8p4+dfsg-1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 5× in last 7d / 21× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 137 total refreshes for this CVE.

  1. 2026-08-25 13:44 UTCEPSS rescore
  2. 2026-08-23 00:13 UTCEPSS rescore
  3. 2026-08-21 23:44 UTCEPSS rescore
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  12. 2026-08-10 06:40 UTCOSV refresh
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  24. 2026-07-25 07:11 UTCOSV refresh
  25. 2026-07-24 14:13 UTCEPSS rescore
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  1. 2026-07-23 14:14 UTCEPSS rescore
  2. 2026-07-23 01:19 UTCEG score recompute
  3. 2026-07-23 00:21 UTCEG score recompute
  4. 2026-07-22 21:59 UTCEG score recompute
  5. 2026-07-22 14:04 UTCEPSS rescore
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  20. 2026-07-12 05:42 UTCEPSS rescore
  21. 2026-07-11 08:23 UTCEPSS rescore
  22. 2026-07-09 19:05 UTCEPSS rescore
  23. 2026-07-09 19:05 UTCEPSS rescore
  24. 2026-07-08 15:10 UTCEPSS rescore
  25. 2026-07-08 02:05 UTCOSV refresh
  26. 2026-07-07 13:42 UTCEPSS rescore
  27. 2026-07-07 13:42 UTCEPSS rescore
  28. 2026-07-06 16:24 UTCEPSS rescore
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  46. 2026-06-21 01:57 UTCEPSS rescore
  47. 2026-06-21 01:57 UTCEPSS rescore
  48. 2026-06-19 13:55 UTCOSV refresh
  49. 2026-06-18 17:50 UTCEPSS rescore
  50. 2026-06-17 17:50 UTCEPSS rescore
  51. 2026-06-17 17:49 UTCEPSS rescore
  52. 2026-06-16 17:50 UTCEPSS rescore
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  54. 2026-06-15 17:45 UTCEPSS rescore
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  71. 2026-06-01 13:49 UTCEPSS rescore
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  73. 2026-05-31 22:28 UTCEPSS rescore
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  75. 2026-05-31 00:14 UTCEPSS rescore

Frequently asked(5)

What is CVE-2015-7853?
CVE-2015-7853 is a critical vulnerability published on August 7, 2017. The datalen parameter in the refclock driver in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to execute arbitrary code or cause a denial of service (crash) via a negative input value.
When was CVE-2015-7853 disclosed?
CVE-2015-7853 was first published in the National Vulnerability Database on August 7, 2017, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2015-7853 actively exploited?
CVE-2015-7853 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 12% probability of exploitation in the next 30 days, which ranks it in the top 4.2% of all scored CVEs.
What is the CVSS score of CVE-2015-7853?
CVE-2015-7853 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2015-7853?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2015-7853, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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