CVE-2026-70453 rsync < 3.5.0 Algorithmic Complexity DoS via hash_search()
Remote attackers can cause denial of service in rsync by sending crafted file lists that trigger quadratic-time hash lookups, exhausting CPU resources.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-70453?
CVE-2026-70453 is a high-severity denial of service vulnerability in RsyncProject rsync, published on 13 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
rsync before 3.5.0 contains an algorithmic complexity vulnerability in the hash_search() function that allows a remote attacker to cause a denial of service by delivering a carefully constructed file list. A sender can exploit the quadratic-time worst-case behavior in hash lookups to exhaust receiver CPU resources with a modest number of crafted entries, causing a sustained denial of service.
Weakness: CWE-407
Which versions are affected by CVE-2026-70453?
How do I fix CVE-2026-70453?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-70453 being exploited?
There is no known exploitation of CVE-2026-70453 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-70453, AZL-95855, BELL-CVE-2026-70453, DEBIAN-CVE-2026-70453, ECHO-079f-04d3-1628, GHSA-8x5r-mjx8-83hv and 2 more.