CVE-2026-70455
rsync 3.4.2 < 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion
- State
- Published
- Severity
- 8.7 High
- Published
- Aug 13, 2026
- Updated
- Aug 14, 2026
- Reserved
- Aug 4, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 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 | VulnCheck |
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | VulnCheck |
Weaknesses
- CWE-770 Allocation of Resources Without Limits or Throttling
Affected Products
| Product | Versions |
|---|---|
rsyncRsyncProject |
|
References
- GitHub Security Advisory (GHSA-rjvj-qgqg-cvx9)vendor-advisory
- rsync 3.5.0 Release Notesrelease-notes
- https://www.vulncheck.com/advisories/rsync-dos-via-zt-zstandard-compression-thread-exhaustionthird-party-advisory
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