Resource exhaustion in Rsyncproject Rsync
CVE-2026-70455
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.008 (54.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 54th percentile — 54.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.008 · change: +0.003
Affected products
- Rsyncproject Rsync — versions 3.4.2, 3.5.0
- Samba Rsync
Weakness classification (CWE)
References
- github.com/RsyncProject/rsync/releases/tag/v3.5.0 (release-notes, Product, Release Notes)
- github.com/RsyncProject/rsync/security/advisories/GHSA-rjvj-qgqg-cvx9 (vendor-advisory, Vendor Advisory)
- www.vulncheck.com/advisories/rsync-dos-via-zt-zstandard-compression-thread-exha… (Third Party Advisory, Release Notes, third-party-advisory)
Frequently asked questions
- What is CVE-2026-70455?
- CVE-2026-70455 is a high-severity vulnerability in Rsyncproject Rsync, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-08-13.
- How severe is CVE-2026-70455?
- High severity. CVSS v3 base score is 7.5 out of 10.