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rsync CVE-2026-44510

| EUVDEUVD-2026-46111 MEDIUM
Out-of-bounds Read (CWE-125)
2026-07-20 GitHub_M
6.5
CVSS 3.1 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
6.5 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
vuln.today AI
6.5 MEDIUM

Network-delivered crash requires victim-initiated pull (UI:R, PR:N); confirmed crash-only impact on glibc yields C:N/I:N and A:H.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

3
Patch available
Jul 20, 2026 - 23:18 EUVD
Analysis Generated
Jul 20, 2026 - 21:46 vuln.today
CVE Published
Jul 20, 2026 - 21:03 cve.org
MEDIUM 6.5

DescriptionCVE.org

Rsync is a file-copying tool that uses a delta-transfer algorithm to synchronize remote and local files. In versions prior to 3.4.3, the receiver-side out-of-bounds array read in rsync's recv_files() lets a malicious rsync server (or any peer acting in the sender role) deterministically crash any rsync client that pulls from it. The trigger is fully wire-protocol-level, requires no special options on the victim, and works for both rsync:// URLs and remote-shell pulls; since inc_recurse is the protocol-30+ default, any client doing a normal recursive pull against an attacker-controlled URL is exposed. A malicious server sets CF_INC_RECURSE, sends a flist whose first sorted entry is not the leading "." directory (causing parent_ndx to be set to -1), then sends a transfer record with ndx = 0 and an iflag omitting ITEM_TRANSFER, causing the receiver to read 8 bytes before the allocated pointer array and dereference the result in f_name(). The impact is crash-only: the out-of-bounds read lands in glibc mmap chunk metadata and dereferences to an unmapped low address, producing a SEGV that cannot be leveraged into an exploit (confirmed on glibc x86-64 Linux; non-glibc allocators not audited). This issue is fixed in version 3.4.3.

AnalysisAI

rsync client versions prior to 3.4.3 crash deterministically when connecting to a malicious sender due to an out-of-bounds array read in recv_files(). Any client performing a standard recursive pull - the default behavior since protocol version 30 - against an attacker-controlled rsync server or URL is exposed without any special victim-side configuration. Impact is strictly denial-of-service (client crash via SIGSEGV); remote code execution has been explicitly ruled out on glibc x86-64 Linux, though non-glibc allocators remain unaudited. No public exploit identified at time of analysis; vendor-released patch is available in version 3.4.3.

Technical ContextAI

The vulnerability resides in rsync's recv_files() function and is classified as CWE-125 (Out-of-bounds Read). rsync protocol version 30 introduced incremental recursion (inc_recurse), which is the default mode for modern rsync and requires the transmitted file list to be sorted with a leading '.' directory entry. A malicious sender violates this invariant by sending a flist whose first sorted entry is not '.', which causes the receiver to initialize parent_ndx to -1. When a subsequent transfer record arrives with ndx=0 and an iflag that omits ITEM_TRANSFER, recv_files() dereferences a pointer 8 bytes before the start of the allocated pointer array and passes it to f_name(). On glibc x86-64 Linux this lands in mmap chunk header metadata and the resulting pointer dereference hits an unmapped low address, producing SIGSEGV. The trigger is entirely wire-protocol-level - no special rsync options, daemon configuration, or authentication state on the victim side are required. Affected product per CPE: cpe:2.3:a:rsyncproject:rsync:*:*:*:*:*:*:*:* (all versions prior to 3.4.3).

RemediationAI

Upgrade rsync to version 3.4.3 or later, which contains the fix for this out-of-bounds array read; this is the only confirmed remediation per the vendor advisory at https://github.com/RsyncProject/rsync/security/advisories/GHSA-28pw-r563-rxvm. If immediate upgrade is not feasible, restrict rsync client usage to verified, trusted server endpoints only - avoid rsync:// URLs from untrusted sources and ensure remote-shell pulls target only allowlisted hosts. Adding egress firewall rules to block rsync port 873/TCP to non-approved IP ranges reduces the attack surface for rsync:// connections but does not protect SSH-tunneled (remote-shell) pulls, which would require SSH access controls instead. These compensating controls require ongoing operational discipline to maintain and do not address the underlying protocol vulnerability.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Micro 5.3 Affected
SUSE Linux Enterprise Micro 5.4 Affected
SUSE Linux Enterprise Micro 5.5 Affected

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CVE-2026-44510 vulnerability details – vuln.today

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