CVE-2026-53791

CRITICAL

9.1

CVSS v3

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.

CWE-290

How to fix

Remediation Available

rsyncDebian

Fixed in:3.5.0+ds1-1CVE-2026-53791

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

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 ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

0.47%probability of exploitation in 30 days

39thpercentile

Low risk: more likely to be exploited than 39% of all known CVEs.

References

Other references3

Related Vulnerabilities

Other CWE-290 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-4358	Critical	9.8	97%	KEV	-
CVE-2022-24112	Critical	9.8	96%	KEV	Fix
CVE-2022-23131	Critical	9.1	96%	KEV	-
CVE-2019-1234	High	7.5	74%	-	-
CVE-2021-31195	Medium	6.5	74%	-	Fix
CVE-2021-29441	High	8.6	70%	-	Fix

Common questions

How do I fix CVE-2026-53791?

Upgrade rsync on debian unstable to 3.5.0+ds1-1 or later.

Is CVE-2026-53791 being actively exploited?

Not that we know of. CVE-2026-53791 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.47% is the estimated probability that it will be exploited in the next 30 days. That is higher than 39% of all scored CVEs.

How severe is CVE-2026-53791?

CVE-2026-53791 has a CVSS v3 base score of 9.1, rated critical. 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-2026-53791 affect?

Published advisories record a fix for rsync (Debian). 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 2026-08-14.