CVE-2026-70455: CWE-770 Allocation of Resources Without Limits or Throttling in RsyncProject rsync
rsync 3.4.2 before 3.5.0 contains a denial of service vulnerability that allows a remote sender to exhaust system resources by specifying the --zt short alias for --compress-threads, which bypasses the refuse options directive's string matching on long option names. Attackers can specify --zt=N with a large value to spawn an unbounded number of Zstandard worker threads on the receiver, exhausting available thread and memory resources.
AI Analysis
Technical Summary
The vulnerability in rsync 3.4.2 before 3.5.0 (specifically 3.4.2 to 3.4.4) involves improper allocation of resources without limits or throttling (CWE-770). An attacker can specify the short alias --zt=N for --compress-threads with a large N value, which bypasses the refuse options directive's string matching on long option names. This causes the receiver to spawn an unbounded number of Zstandard compression worker threads, leading to exhaustion of thread and memory resources and resulting in a denial of service condition.
Potential Impact
A remote attacker can cause a denial of service by exhausting system thread and memory resources on the rsync receiver, potentially disrupting legitimate synchronization operations.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid using affected rsync versions or restrict usage of the --zt/--compress-threads option from untrusted senders.
CVE-2026-70455: CWE-770 Allocation of Resources Without Limits or Throttling in RsyncProject rsync
Description
rsync 3.4.2 before 3.5.0 contains a denial of service vulnerability that allows a remote sender to exhaust system resources by specifying the --zt short alias for --compress-threads, which bypasses the refuse options directive's string matching on long option names. Attackers can specify --zt=N with a large value to spawn an unbounded number of Zstandard worker threads on the receiver, exhausting available thread and memory resources.
CVSS v4.0
Score 8.7high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in rsync 3.4.2 before 3.5.0 (specifically 3.4.2 to 3.4.4) involves improper allocation of resources without limits or throttling (CWE-770). An attacker can specify the short alias --zt=N for --compress-threads with a large N value, which bypasses the refuse options directive's string matching on long option names. This causes the receiver to spawn an unbounded number of Zstandard compression worker threads, leading to exhaustion of thread and memory resources and resulting in a denial of service condition.
Potential Impact
A remote attacker can cause a denial of service by exhausting system thread and memory resources on the rsync receiver, potentially disrupting legitimate synchronization operations.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid using affected rsync versions or restrict usage of the --zt/--compress-threads option from untrusted senders.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-08-04T14:52:23.814Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a7ddecabf8831d5395d005c
Added to database: 08/13/2026, 15:12:10 UTC
Last enriched: 08/13/2026, 15:29:30 UTC
Last updated: 08/13/2026, 18:08:46 UTC
Views: 6
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