CVE-2026-43617
Rsync < 3.4.3 Authorization Bypass via Hostname Resolution
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.
INFO
Published Date :
May 20, 2026, 2:16 a.m.
Last Modified :
May 21, 2026, 8:54 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Rsync to a version that addresses the vulnerability.
- Review and strengthen rsync daemon access controls.
- Ensure proper PTR record configuration for reverse DNS.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-43617.
| URL | Resource |
|---|---|
| https://github.com/RsyncProject/rsync/releases/tag/v3.4.3 | Release Notes |
| https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjfm-3w2m-jf4f | Vendor Advisory |
| https://www.vulncheck.com/advisories/rsync-authorization-bypass-via-hostname-resolution | Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-43617 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-43617
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-43617 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-43617 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 21, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:samba:rsync:*:*:*:*:*:*:*:* versions up to (including) 3.4.2 Added Reference Type VulnCheck: https://github.com/RsyncProject/rsync/releases/tag/v3.4.3 Types: Release Notes Added Reference Type VulnCheck: https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjfm-3w2m-jf4f Types: Vendor Advisory Added Reference Type VulnCheck: https://www.vulncheck.com/advisories/rsync-authorization-bypass-via-hostname-resolution Types: Third Party Advisory -
New CVE Received by [email protected]
May. 20, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 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 Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N Added CWE CWE-289 Added Reference https://github.com/RsyncProject/rsync/releases/tag/v3.4.3 Added Reference https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjfm-3w2m-jf4f Added Reference https://www.vulncheck.com/advisories/rsync-authorization-bypass-via-hostname-resolution