Description
chronyd in Chrony before 1.23.1, and possibly 1.24-pre1, generates a syslog message for each unauthorized cmdmon packet, which allows remote attackers to cause a denial of service (disk consumption) via a large number of invalid packets.
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 | chrony | 1.23-7 | — |
| Debian 13 | chrony | 1.23-7 | — |
| Debian 12 | chrony | 1.23-7 | — |
| Debian 5.0 | chrony | 1.23-6+lenny1 | DSA-1992-1 |
| Debian 4.0 | chrony | 1.21z-5+etch1 | DSA-1992-1 |
Advisories 1
- DSA-1992-1 chrony - denial of service Debian Security (DSA / DLA) · Mar 9, 2026
References
- DSA-1992 vendor-advisory
- 38106 vdb-entry
- http://chrony.tuxfamily.org/News.html
- 38428 third-party-advisory
- http://git.tuxfamily.org/chrony/chrony.git/?p=gitroot/chrony/chrony.git%3Ba=commit%3Bh=0b710499f994823bd938fc6895f097eefb9cc59f
- https://bugzilla.redhat.com/show_bug.cgi?id=555367
- 38480 third-party-advisory