CVE & CISA-KEV Catalog

CVE-2026-43617

MEDIUM
4.8
CVSS v3
NVD

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.

CWE-289

How to fix

Remediation Available
rsyncDebian
Fixed in:3.2.3-4+deb11u4CVE-2026-43617
Fixed in:3.2.7-1+deb12u5CVE-2026-43617
Fixed in:3.4.1+ds1-5+deb13u3CVE-2026-43617
Fixed in:3.4.3+ds1-1CVE-2026-43617
rsyncUbuntu
Fixed in:3.1.0-2ubuntu0.4+esm3USN-8349-1
Fixed in:3.1.1-3ubuntu1.3+esm5USN-8349-1
Fixed in:3.1.2-2.1ubuntu1.6+esm3USN-8349-1
Fixed in:3.1.3-8ubuntu0.9+esm1USN-8349-1
Fixed in:3.2.7-0ubuntu0.22.04.6USN-8283-1
Fixed in:3.2.7-1ubuntu1.4USN-8283-1
Fixed in:3.4.1+ds1-5ubuntu1.2USN-8283-1

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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityLow
IntegrityLow
AvailabilityNone

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

Exploit Intelligence

0.28%probability of exploitation in 30 days
20thpercentile

Low risk: more likely to be exploited than 20% of all known CVEs.

References

Vendor Advisory1
Third-Party Advisory1
Release Notes1

Related Vulnerabilities

Other CWE-289 vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2024-56511Critical9.844%-Fix
CVE-2021-34746Critical9.818%-Fix
CVE-2017-16590High8.83.3%--
CVE-2026-48618Medium6.53.2%-Fix
CVE-2025-55130Critical9.11.6%-Fix
CVE-2026-44492High8.60.9%-Fix

Common questions

How do I fix CVE-2026-43617?

Published advisories record a fix for 2 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2026-43617 being actively exploited?

Not that we know of. CVE-2026-43617 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.28% is the estimated probability that it will be exploited in the next 30 days. That is higher than 20% of all scored CVEs.

How severe is CVE-2026-43617?

CVE-2026-43617 has a CVSS v3 base score of 4.8, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-43617 affect?

Published advisories record a fix for rsync (Debian), rsync (Ubuntu). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-24.