CVE-2015-7871

critical

Published 2017-08-07 · Modified 2026-05-13

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CVSS v3

9.8

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

CVSS v4 NEW

—

not yet in upstream

VIR risk

10.0

Description

Crypto-NAK packets in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to bypass authentication.

Predictions

Exploit likelihood

97%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

Exploits

Public proof-of-concept code below. AS-IS, for defenders and authorised testing only.

Metasploit modules

auxiliary_scanner/ntp/ntp_nak_to_the_future rank 300

NTP "NAK to the Future"

Source fetch failed: fetch_error — view the original via the link above.

OS impact

Debian Mixed 4 releases

Version	Status	Fixed in
bullseye	Fixed	`1:4.2.8p4+dfsg-1`
9.0	Affected	—
8.0	Affected	—
7.0	Affected	—

Application impact

Vendor	Product	Versions	Fixed
ntp	ntp	`{"startIncluding":"4.2.6","endExcluding":"4.2.8"}`	`4.2.8`
ntp	ntp	`4.2.5`
ntp	ntp	`4.2.8`
netapp	oncommand_balance	`-`
netapp	oncommand_performance_manager	`-`
netapp	oncommand_unified_manager	`-`

References

CWEs

CWE-287

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.