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Vulnerability record · CVE-2026-70455 · published 13 August 2026

CVE-2026-70455: Samba rsync allocation without limits vulnerability

Samba · 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.

8.7 CVSS 4.0 High EPSS 0.78% · top 45.8% CWE-770 · Allocation without limits
8.7CVSS 4.0 base score
0.78%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References
31 Aug 2026Last modified by NVD

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: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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/RsyncProject/rsync/releases/tag/v3.5.0 ProductRelease Notes
https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjvj-qgqg-cvx9 Vendor Advisory
https://www.vulncheck.com/advisories/rsync-dos-via-zt-zstandard-compression-thread-exhaustion Release NotesThird Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-70455), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.