# CVE-2026-43620: Rsync out-of-bounds array read in recv_files

Source: https://junglewise.ai/threats/cve-2026-43620-rsync-out-of-bounds-array-read-in-recv-files  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-20. Updated: 2026-05-20  
License: CC BY 4.0 with a link back

CVE-2026-43620 · Severity: medium · CVSS 6.5 · Published 2026-05-20

Rsync is a widely used utility for synchronizing files between different systems. A vulnerability in the client-side software allows a malicious server to crash the rsync client during a file transfer. This could be used to disrupt automated backup or deployment processes, though it does not appear to allow for data theft or unauthorized system access.

Technologies: [RsyncProject Rsync](https://junglewise.ai/threats/technologies/rsync). Vendors: [RsyncProject](https://junglewise.ai/threats/vendors/rsyncproject).

## Quick answers

**Is CVE-2026-43620 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-43620 being exploited in the wild.

**How severe is CVE-2026-43620?** Medium severity, with a CVSS score of 6.5, published 20 May 2026.

**Which products and versions are affected?** RsyncProject Rsync <= 3.4.2.

**Is there a fix for CVE-2026-43620?** A patch was published on 2026-05-20: Rsync version 3.4.3 released. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-43620 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-43620?** Check whether you run RsyncProject Rsync at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds array read exists in the recv_files() function within receiver.c. By setting the CF_INC_RECURSE flag and providing a specially crafted file list where the first entry is not the leading dot directory, a malicious sender can cause the receiver to set an internal index (parent_ndx) to -1. When a subsequent transfer record with ndx=0 and specific flags is processed, the receiver attempts to read memory 8 bytes before the allocated pointer array. This results in a null or invalid pointer dereference and a deterministic SIGSEGV crash. The vulnerability is reachable via both rsync:// and remote-shell (SSH) pulls. A fix is available in version 3.4.3, and a workaround is to use the --no-inc-recursive flag.

## Affected products

- RsyncProject rsync <= 3.4.2

## Timeline

- 2026-05-19: disclosed: Vulnerability reported by Pratham Gupta.
- 2026-05-20: patched: Rsync version 3.4.3 released.
- 2026-05-20: advisory

## References

- [https://github.com/RsyncProject/rsync/releases/tag/v3.4.3](https://github.com/RsyncProject/rsync/releases/tag/v3.4.3)
- [https://github.com/RsyncProject/rsync/security/advisories/GHSA-28pw-r563-rxvm](https://github.com/RsyncProject/rsync/security/advisories/GHSA-28pw-r563-rxvm)
- [https://www.vulncheck.com/advisories/rsync-out-of-bounds-array-read-via-recv-files](https://www.vulncheck.com/advisories/rsync-out-of-bounds-array-read-via-recv-files)

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- [rsync denial of service in hash_search()](https://junglewise.ai/threats/cve-2026-119741-rsync-through-3-5-1-contains-a-denial-of-service-vulnerability)
- [Rsync out-of-bounds read in recv_files](https://junglewise.ai/threats/cve-2026-44510-rsync-out-of-bounds-read-in-recv-files)
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