4.2.6 Release Announcement
Last update: June 28, 2022 21:06 UTC (1f97faf40)
The NTP Public Services Project is pleased to announce that NTP 4.2.6, a Stable Release of the NTP Reference Implementation from the NTP Project, is now available.
Focus: Security Fixes
Severity: HIGH
This release fixes the following high-severity vulnerability:
NTP mode 7 (MODE_PRIVATE) is used by the ntpdc query and control utility. In contrast, ntpq uses NTP mode 6 (MODE_CONTROL), while routine
NTP time transfers use modes 1 through 5. Upon receipt of an incorrect mode 7 request or a mode 7 error response from an address which is not
listed in a restrict ... noquery or restrict ... ignore statement, ntpd will reply with a mode 7 error response (and log a message). In
this case:
- If an attacker spoofs the source address of
ntpd host A in a mode 7 response packet sent to ntpd host B, both A and B will continuously send
each other error responses, for as long as those packets get through.
- If an attacker spoofs an address of
ntpd host A in a mode 7 response packet sent to ntpd host A, A will respond to itself endlessly,
consuming CPU and logging excessively.
Credit for finding this vulnerability goes to Robin Park and Dmitri Vinokurov of Alcatel-Lucent.