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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.57%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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
- 8.7 HIGHCVSS: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/M
- EPSS
- 0.57% probability · 45th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-770
- Affected
- samba/rsync
- Source
- disclosure@vulncheck.com
References
- https://github.com/RsyncProject/rsync/releases/tag/v3.5.0Product, Release Notes
- https://github.com/RsyncProject/rsync/security/advisories/GHSA-rjvj-qgqg-cvx9Vendor Advisory
- https://www.vulncheck.com/advisories/rsync-dos-via-zt-zstandard-compression-thread-exhaustionRelease Notes, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.