Vulnerability in Rsyncproject Rsync
CVE-2026-43617
Rsync version 3.4.2 and prior contain an authorization bypass vulnerability in the rsync daemon's hostname-based access control list enforcement when configured with chroot. Attackers can bypass hostname-based deny rules by controlling the PTR record for their source IP address, allowing connections from hostnames that administrators intended to deny when reverse DNS resolution fails and defaults to UNKNOWN.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (22.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 22.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000
Affected products
- Rsyncproject Rsync — versions 0
- Samba Rsync
Weakness classification (CWE)
References
- github.com/RsyncProject/rsync/security/advisories/GHSA-rjfm-3w2m-jf4f (vendor-advisory, Vendor Advisory)
- github.com/RsyncProject/rsync/releases/tag/v3.4.3 (release-notes, Release Notes)
- www.vulncheck.com/advisories/rsync-authorization-bypass-via-hostname-resolution (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-43617?
- CVE-2026-43617 is a medium-severity vulnerability in Rsyncproject Rsync, classified under CWE-289. CVSS score: 4.8/10. Published 2026-05-20.
- How severe is CVE-2026-43617?
- Medium severity. CVSS v3 base score is 4.8 out of 10.