Description
A flaw was found in chrony versions before 3.5.1 when creating the PID file under the /var/run/chrony folder. The file is created during chronyd startup while still running as the root user, and when it's opened for writing, chronyd does not check for an existing symbolic link with the same file name. This flaw allows an attacker with privileged access to create a symlink with the default PID file name pointing to any destination file in the system, resulting in data loss and a denial of service due to the path traversal.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | Chrony | All chrony versions before 3.5.1 | — |
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 | 3.5.1-1 | — |
| Debian 13 | chrony | 3.5.1-1 | — |
| Debian 12 | chrony | 3.5.1-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | chrony | 3.5-6ubuntu6.2 | USN-4475-1 |
| Ubuntu 18.04 LTS | chrony | 3.2-4ubuntu4.5 | USN-4475-1 |
| Ubuntu 16.04 LTS | chrony | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 14.04 LTS | chrony | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP3 | augeas | 1.10.1-3.9.1 | SUSE-SU-2022:0845-1 |
| SLES 15 SP3 | chrony | 4.1-150300.16.3.1 | SUSE-SU-2022:0845-1 |
| SLES 12 SP5 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
| SLES 12 SP4 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
| SLES 12 SP3 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
| SLES 12 SP2 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
Show 13 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP5 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
| SLES for SAP 12 SP4 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
| SLES for SAP 12 SP3 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
| SLE Real Time 15 SP2 | augeas | 1.10.1-3.9.1 | SUSE-SU-2022:0845-1 |
| SLE Micro 5.2 | augeas | 1.10.1-3.9.1 | SUSE-SU-2022:0845-2 |
| SLE Micro 5.1 | augeas | 1.10.1-3.9.1 | SUSE-SU-2022:0845-1 |
| SLE Micro 5.1 | chrony | 4.1-150300.16.3.1 | SUSE-SU-2022:0845-1 |
| SLE Micro 5.0 | augeas | 1.10.1-3.9.1 | SUSE-SU-2022:0845-1 |
| SUSE OpenStack Cloud Crowbar 9 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
| SUSE OpenStack Cloud Crowbar 8 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
| SUSE OpenStack Cloud 9 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
| SUSE OpenStack Cloud 8 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
| SUSE Linux Enterprise Installer Updates 15 SP3 | augeas | 1.10.1-3.9.1 | SUSE-SU-2022:0845-1 |
| SUSE HPE Helion OpenStack 8 | chrony | 4.1-5.9.1 | SUSE-SU-2021:4147-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | chrony | 4.1-5.2 | openSUSE-SU-2024:10682-1 |
| openSUSE Leap 15.3 | augeas | 1.10.1-3.9.1 | openSUSE-SU-2022:0845-1 |
| openSUSE Leap 15.3 | chrony | 4.1-150300.16.3.1 | openSUSE-SU-2022:0845-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | chrony | 3.5.1-r0 | — |
| Alpine v3.23 | chrony | 3.5.1-r0 | — |
| Alpine v3.22 | chrony | 3.5.1-r0 | — |
| Alpine v3.21 | chrony | 3.5.1-r0 | — |
| Alpine v3.20 | chrony | 3.5.1-r0 | — |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | chrony | 3.5.1-r0 | — |
| Alpine v3.18 | chrony | 3.5.1-r0 | — |
| Alpine v3.17 | chrony | 3.5.1-r0 | — |
| Alpine v3.16 | chrony | 3.5.1-r0 | — |
| Alpine v3.15 | chrony | 3.5.1-r0 | — |
| Alpine v3.14 | chrony | 3.5.1-r0 | — |
| Alpine v3.13 | chrony | 3.5.1-r0 | — |
| Alpine v3.12 | chrony | 3.5.1-r0 | — |
| Alpine v3.11 | chrony | 3.5.1-r0 | — |
| Alpine v3.10 | chrony | 3.5.1-r0 | — |
| Alpine v3.9 | chrony | 3.4-r2 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | chrony | 3.5.1-1.amzn2.0.1 | ALAS2-2021-1575 |
Advisories 7
- USN-4475-1 chrony vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- SUSE-SU-2022:0845-2 Security update for chrony SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10682-1 chrony-4.1-5.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:4147-1 Security update for chrony SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2022:0845-1 Security update for chrony SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:0845-1 Security update for chrony SUSE / openSUSE Security Updates · Feb 4, 2026
- ALAS2-2021-1575 Moderate: chrony security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Jan 7, 2021
References
- FEDORA-2020-7aa962c55e vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1870298
- GLSA-202008-23 vendor-advisory
- USN-4475-1 vendor-advisory