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rsync CVE-2026-70453

| EUVDEUVD-2026-58051 HIGH
Inefficient Algorithmic Complexity (CWE-407)
2026-08-13 VulnCheck
8.7
CVSS 4.0 · Vendor: VulnCheck
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Severity by source

Vendor (VulnCheck) PRIMARY
8.7 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/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
7.5 HIGH

Network-reachable with no auth or complexity prerequisites; impact is CPU exhaustion on the receiver (availability only); no confidentiality or integrity impact; scope unchanged as only the receiver process is affected.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/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
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

3
Source Code Evidence Fetched
Aug 13, 2026 - 15:45 vuln.today
Analysis Generated
Aug 13, 2026 - 15:45 vuln.today
CVE Published
Aug 13, 2026 - 14:46 cve.org
HIGH 8.7

DescriptionCVE.org

rsync before 3.5.0 contains an algorithmic complexity vulnerability in the hash_search() function that allows a remote attacker to cause a denial of service by delivering a carefully constructed file list. A sender can exploit the quadratic-time worst-case behavior in hash lookups to exhaust receiver CPU resources with a modest number of crafted entries, causing a sustained denial of service.

AnalysisAI

CPU exhaustion in rsync receivers before 3.5.0 allows a remote sender to cause denial of service by exploiting quadratic-time worst-case behavior in the hash_search() function (CWE-407). A malicious or compromised sender delivers a carefully crafted file list - requiring only a modest number of entries - to collapse hash lookup performance and sustain receiver CPU exhaustion for the duration of the sync session. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Connect to target rsync receiver as sender (no auth required)
Delivery
Craft file list with hash-colliding entries targeting hash_search()
Exploit
Transmit crafted file list over rsync protocol
Execution
Trigger O(n²) CPU exhaustion in receiver hash_search()
Impact
Sustain receiver DoS for session duration

Vulnerability AssessmentAI

Exploitation The attacker must control or impersonate the rsync sender role - either by operating a rogue rsync server that a victim client connects to (pull mode, no authentication required per CVSS PR:N) or by acting as an authorized client pushing a crafted file list to a receiver (push mode, which may require valid rsync credentials depending on server configuration). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 4.0 score of 8.7 with vector AV:N/AC:L/AT:N/PR:N/UI:N/VA:H reflects a network-reachable, zero-complexity vulnerability requiring no authentication, targeting availability only. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker operates a malicious rsync server and advertises it as a legitimate source; when a victim client initiates a pull-mode sync, the rogue server returns a crafted file list containing entries engineered to collide in the receiver's hash table. The receiver's hash_search() function processes each entry with quadratic-time complexity, consuming all available CPU for the duration of the sync session and preventing legitimate sync operations from completing. …
Remediation Upgrade rsync to version 3.5.0 or later; this is the vendor-released patch confirmed by the RsyncProject GitHub release tag and security advisory GHSA-8x5r-mjx8-83hv (https://github.com/RsyncProject/rsync/releases/tag/v3.5.0). … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, inventory all rsync receivers and senders across backup, file-sync, and disaster-recovery infrastructure, then restrict network access to rsync services (port 873) to trusted hosts only using firewall rules. …

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Vendor StatusVendor

SUSE

Severity: Important
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-2026-70453 vulnerability details – vuln.today

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