# 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.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **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:** Yes
- **Published:** 20 May 2026
- **Updated:** 14 Jul 2026
- **Also known as:** ALPINE-CVE-2026-43620, AZL-86991, BELL-CVE-2026-43620, CLSA-2026-1779462894, CVE-2026-44510, DEBIAN-CVE-2026-43620, ECHO-1f95-ed49-f41f, GHSA-28pw-r563-rxvm, GHSA-jmf6-74r8-6c28, JLSEC-2026-631, OESA-2026-2549, OESA-2026-2551, OESA-2026-2552, UBUNTU-CVE-2026-43620

## 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 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-43620?

It affects 1 product.


Products: Samba Rsync.

## How do I fix CVE-2026-43620?

Upgrade to a fixed version.

## 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](https://insights.sbomify.com/CVE-2017-15994/): Security feature bypass in n/a (critical 9.8)
- [CVE-2026-53791](https://insights.sbomify.com/CVE-2026-53791/): rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header (critical 9.1)
- [CVE-2026-70461](https://insights.sbomify.com/CVE-2026-70461/): rsync 3.2.5 < 3.5.0 Heap Out-of-Bounds Write via files-from Entry (high 8.8)
- [CVE-2026-70455](https://insights.sbomify.com/CVE-2026-70455/): rsync 3.4.2 < 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion (high 8.7)
- [CVE-2026-70463](https://insights.sbomify.com/CVE-2026-70463/): rsync 3.1.0 < 3.5.0 Authorization Bypass via auth users Directive Parsing (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43620 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-43620 in the wild and no public exploit code.

Affected product: RsyncProject rsync. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-43620/ (Markdown: https://insights.sbomify.com/CVE-2026-43620/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43620
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43620
- OSV: https://osv.dev/vulnerability/CVE-2026-43620

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43620/
Summaries are generated and may contain mistakes; the official description above is the record.