Description
chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service (inability to synchronize) via random timestamps in crafted NTP data packets.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| chrony | chrony | before 1.31.1 | — |
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 | 1.30-2 | — |
| Debian 13 | chrony | 1.30-2 | — |
| Debian 12 | chrony | 1.30-2 | — |
| Debian 7 | chrony | 1.24-3.1+deb7u3 | DSA-3222-1 |
| Debian 6.0 | chrony | 1.24-3+squeeze2 | DLA-193-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 14.04 LTS | chrony | 1.29-1ubuntu0.1 | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7 | chrony | 2.1.1-1.el7 | RHSA-2015:2241 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | chrony | 2.1.1-1.el7 | ELSA-2015-2241 |
Advisories 4
- RHSA-2015:2241 Red Hat Security Advisory: chrony security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Jun 27, 2026
- DLA-193-1 chrony - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3222-1 chrony - security update Debian Security (DSA / DLA) · Mar 9, 2026
- ELSA-2015-2241 Moderate: chrony security, bug fix, and enhancement update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Nov 23, 2015