VulnerabilityAnalyzed

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.

MEDIUM 6.3EPSS 0.28%

Does this matter?

Lower severity and a low EPSS score (0.28%). Track it; it rarely justifies an emergency change on its own.

Description

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.

CVSS 4.0: 6.3 MEDIUMCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.28% probability · 21th percentile
CISA KEV: Not listed
Weakness: CWE-289
Affected: samba/rsync
Source: disclosure@vulncheck.com

References

https://github.com/RsyncProject/rsync/releases/tag/v3.4.3Release Notes
https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjfm-3w2m-jf4fVendor Advisory
https://www.vulncheck.com/advisories/rsync-authorization-bypass-via-hostname-resolutionThird Party Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.