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CVE-2026-53791

Samba Rsync authentication bypass

9.1 CRITICALEPSS 0.50%
  1. Published13 Aug 2026

Description

rsync daemon before 3.5.0 contains an IP address spoofing vulnerability that allows unauthenticated remote attackers to bypass IP-based access controls by sending a crafted PROXY protocol header with a forged source address. Attackers who can connect directly to the rsync daemon can inject a spoofed source IP in the PROXY protocol header to circumvent hosts allow/deny rules, gaining unauthorized access that would otherwise be blocked based on their real source address.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

Samba Rsync< 3.5.0

Remediation

Fixed in
Samba Rsync≥ 3.5.0

References

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Frequently asked

Is CVE-2026-53791 being actively exploited?

CVE-2026-53791 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.50%.

How severe is CVE-2026-53791?

CVE-2026-53791 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.50% probability of exploitation.

Which products are affected by CVE-2026-53791?

Affected products include Samba Rsync.

How do I fix CVE-2026-53791?

Upgrade affected software to a fixed version, for example Samba Rsync 3.5.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-53791 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.