CVE-2026-70455
rsync 3.4.2 < 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-770 |
| Vendor | rsyncproject |
| Product | rsync |
| Published | Aug 13, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
RsyncProject / rsync
3.4.2 ≤ 3.4.4
References
Credits
fcasal