CVE-2026-43617

Name: CVE-2026-43617
Creator: NVD / NIST
Published: 2026-05-20T02:16:36.233+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.3/10EPSS 0.28%

Last modified Jun 17, 2026

CVE-2026-43617 is a medium-severity vulnerability rated 6.3/10 on the CVSS scale. 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.. EPSS estimates a 0.28% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

4.8/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS 4.0

6.3/10

CVSS: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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability

0.28%

19.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-289

Affected Software

Vendor	Product	Versions
Samba	Rsync	<= 3.4.2

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

Timeline

Published: May 20, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-43617?

How severe is CVE-2026-43617?

CVE-2026-43617 has a CVSS score of 6.3/10 (MEDIUM severity). The EPSS model estimates a 0.28% probability of exploitation in the next 30 days.

How do I fix CVE-2026-43617?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-43617?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST