CVE-2026-43620 Rsync < 3.4.3 Out-of-Bounds Array Read via recv_files()
A malicious rsync server can crash the rsync client via an out-of-bounds read in recv_files, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-43620?
CVE-2026-43620 is a medium-severity memory corruption vulnerability in RsyncProject rsync, published on 20 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Rsync version 3.4.2 and prior contain a receiver-side out-of-bounds array read vulnerability in recv_files() in receiver.c that allows a malicious rsync server to crash the rsync client process. Attackers can exploit the vulnerability by setting CF_INC_RECURSE in compatibility flags and sending a specially crafted file list where the first sorted entry is not the leading dot directory, followed by a transfer record with ndx=0 and an iflag word without ITEM_TRANSFER, causing the receiver to read 8 bytes before the allocated pointer array and dereference an invalid pointer at an unmapped address, resulting in a deterministic SIGSEGV crash of the rsync client.
Weakness: CWE-125
Which versions are affected by CVE-2026-43620?
It affects 1 product.
Products include Samba Rsync.
How do I fix CVE-2026-43620?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-43620 being exploited?
There is no known exploitation of CVE-2026-43620 in the wild and no public exploit code.
Other vulnerabilities in RsyncProject rsync
- CVE-2017-15994 Security feature bypass in n/a
- CVE-2026-53791 rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header
- CVE-2026-70461 rsync 3.2.5 < 3.5.0 Heap Out-of-Bounds Write via files-from Entry
- CVE-2026-70455 rsync 3.4.2 < 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion
- CVE-2026-70463 rsync 3.1.0 < 3.5.0 Authorization Bypass via auth users Directive Parsing
Sources
Also known as ALPINE-CVE-2026-43620, AZL-86991, BELL-CVE-2026-43620, CLSA-2026-1779462894, CVE-2026-44510, DEBIAN-CVE-2026-43620 and 8 more.