CVE-2026-43617
Publication date 20 May 2026
Last updated 20 May 2026
Ubuntu priority
Description
On an rsync daemon configured with the global "daemon chroot = /X" rsyncd.conf setting, the reverse-DNS lookup of the connecting client was performed *after* the daemon had chrooted into /X. If /X did not contain the files glibc needs for resolution (/etc/resolv.conf, /etc/nsswitch.conf, /etc/hosts, NSS service modules), the lookup failed and the connecting hostname was set to "UNKNOWN". Hostname-based deny rules ("hosts deny = *.evil.example") therefore could not match, and an attacker controlling their PTR record could connect from a hostname the administrator had intended to deny. IP-based ACLs are unaffected. The per-module "use chroot" setting is unrelated to this issue.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| rsync | 26.04 LTS resolute |
Fixed 3.4.1+ds1-7ubuntu0.2
|
| 25.10 questing |
Fixed 3.4.1+ds1-5ubuntu1.2
|
|
| 24.04 LTS noble |
Fixed 3.2.7-1ubuntu1.4
|
|
| 22.04 LTS jammy |
Fixed 3.2.7-0ubuntu0.22.04.6
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
|
| 14.04 LTS trusty |
Needs evaluation
|
References
Related Ubuntu Security Notices (USN)
- USN-8283-1
- rsync vulnerabilities
- 20 May 2026