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rsync CVE-2026-53792

| EUVDEUVD-2026-58100 HIGH
Improper Validation of Array Index (CWE-129)
2026-08-13 VulnCheck
7.1
CVSS 4.0 · Vendor: VulnCheck
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Severity by source

Vendor (VulnCheck) PRIMARY
7.1 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/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
vuln.today AI
6.5 MEDIUM

Network-reachable with low complexity and no required privileges, but user must initiate the sync; impact is availability only per description.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
6.5 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Red Hat
6.5 MEDIUM
qualitative

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
P
Scope
X

Lifecycle Timeline

3
Source Code Evidence Fetched
Aug 13, 2026 - 15:54 vuln.today
Analysis Generated
Aug 13, 2026 - 15:54 vuln.today
CVE Published
Aug 13, 2026 - 14:38 cve.org
HIGH 7.1

DescriptionCVE.org

rsync before 3.5.0 contains an out-of-bounds read vulnerability in the sender-side block matching logic that allows a malicious receiver to trigger memory access before the start of an allocated buffer by sending a crafted checksum block with a length of zero. Attackers can send a specially crafted checksum set containing a zero-length block to cause a negative offset calculation during delta computation, resulting in an out-of-bounds read of file data buffer memory on the sender side.

AnalysisAI

Out-of-bounds read in rsync's sender-side block matching logic exposes systems running rsync before 3.5.0 to a denial-of-service condition when syncing with a malicious or compromised receiver. The vulnerability stems from missing validation of zero-length checksum blocks: when a receiver sends such a block, the sender performs a negative offset calculation during delta computation, reading memory before the start of an allocated file data buffer. No public exploit code has been identified at time of analysis, and this CVE is not listed in the CISA KEV catalog, but the CVSS 4.0 score of 7.1 (VA:H) reflects the practical crash risk for any rsync client connecting to an untrusted server.

Technical ContextAI

rsync implements the rsync delta-transfer algorithm, where the receiver sends checksum sets describing blocks of its local file copy to the sender, which then computes which blocks differ and transfers only the deltas. The vulnerability (CWE-129: Improper Validation of Array Index) occurs in the sender-side block matching code: the length field of an incoming checksum block is not validated before being used in offset arithmetic. A zero-length block causes a negative offset, causing the sender to read memory before the start of the allocated file data buffer. The affected product is identified by CPE cpe:2.3:a:rsyncproject:rsync:*:*:*:*:*:*:*:* covering all rsync versions prior to 3.5.0 as maintained by the RsyncProject.

RemediationAI

The primary fix is upgrading to rsync 3.5.0, released by the RsyncProject and designated a major security release. The release is available at https://github.com/RsyncProject/rsync/releases/tag/v3.5.0 with full changelog details at https://download.samba.org/pub/rsync/NEWS#3.5.0. Organizations unable to upgrade immediately should restrict rsync client connections to only explicitly trusted, internally controlled servers - enforced via firewall rules or SSH forced-command restrictions - so that no automated job can connect to an unknown or third-party receiver. Disabling rsync daemon mode for untrusted networks and requiring SSH transport with known-host verification reduces the attack surface, though it does not eliminate the vulnerability if a trusted server is itself compromised. Package maintainers on major Linux distributions (RHEL, Debian, Ubuntu, SUSE) should be monitored for backported security patches if in-place upgrades to 3.5.0 are not immediately feasible.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS Affected
SUSE Linux Enterprise Micro 5.3 Affected

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CVE-2026-53792 vulnerability details – vuln.today

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