Description
OpenNTPD before 6.0p1 does not validate the CN for HTTPS constraint requests, which allows remote attackers to bypass the man-in-the-middle mitigations via a crafted timestamp constraint with a valid certificate.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | openntpd | 1:6.0p1-1 | — |
| Debian 13 | openntpd | 1:6.0p1-1 | — |
| Debian 12 | openntpd | 1:6.0p1-1 | — |
References
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.sbin/ntpd/constraint.c.diff?r1=1.27&r2=1.28
- [oss-security] 20160523 CVE request: OpenNTPD not verifying CN during HTTPS constraints request mailing-list
- [oss-security] 20160529 Re: CVE request: OpenNTPD not verifying CN during HTTPS constraints request mailing-list
- http://www.openntpd.org/txt/release-6.0p1.txt