CVE-2026-43620Network attack vector

Client crash via receiver array under-read

Published May 20, 2026 · Updated May 20, 2026

Out-of-bounds read in rsync before 3.4.3 allows remote attackers controlling a sending peer to crash a client during a recursive pull. recv_files() uses ndx=0 after a crafted incremental file list leaves parent_ndx at -1, reading eight bytes before the file-pointer array and dereferencing an invalid pointer. A normal protocol-30-or-later recursive pull needs no special client options; exploitation ends the client process with SIGSEGV without reported data disclosure or modification.

CVSS severity6.9
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in rsync before 3.4.3 allows remote attackers controlling a sending peer to crash a client during a recursive pull. recv_files() uses ndx=0 after a crafted incremental file list leaves parent_ndx at -1, reading eight bytes before the file-pointer array and dereferencing an invalid pointer. A normal protocol-30-or-later recursive pull needs no special client options; exploitation ends the client process with SIGSEGV without reported data disclosure or modification.

The record

CVE
CVE-2026-43620
Published
May 20, 2026
Updated
May 20, 2026
Vendor
Rsync Project
Product
rsync
Classifications
CWE-125, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 20, 2026CVE publishedPublication date reported by the CVE source.
  2. May 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rsync Project · rsyncversion=0 <3.4.3

Published CVSS scores

6.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
6.9VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
6.9UbuntuCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
6.5VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
6.5Rsync ProjectCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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