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🛡️ CVE-2026-43617 — rsync

🟡 CVSS 4.8 — Medium ✅ No Known Exploit CWE-289 NVD
4.8
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity low, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: None.

Weakness class

CVE-2026-43617 is classified as CWE-289: Authentication Bypass by Alternate Name. The product performs authentication based on the name of a resource being accessed, or the name of the actor performing the access, but it does not properly check all possible names for that resource or actor.

Affected software

CVE-2026-43617 is recorded against 1 package.

  • rsync (fixed in 3.4.2)

Timeline and source

Published on 20 May 2026 and last revised on 24 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com
github.com
www.vulncheck.com

Same weakness in other software

These advisories are the same class of weakness (CWE-289: Authentication Bypass by Alternate Name) in other software:

CVE-2026-43617 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity MEDIUM
CVSS Score 4.8
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
CWE CWE-289
Public Exploit ✅ No
Source NVD
Published 2026-05-20
Updated 2026-08-20
Modified 2026-07-24
Fix URL N/A

Affected Packages

Software From version Fixed in
rsync — 3.4.2

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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