CVE-2025-10158 in rsync
Summary
by MITRE • 11/18/2025
A malicious client acting as the receiver of an rsync file transfer can trigger an out of bounds read of a heap based buffer, via a negative array index. The
malicious
rsync client requires at least read access to the remote rsync module in order to trigger the issue.
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Analysis
by VulDB Data Team • 06/02/2026
The vulnerability identified as CVE-2025-10158 represents a critical out-of-bounds read condition within the rsync file transfer protocol implementation that occurs when processing maliciously crafted data from a remote client. This flaw manifests as an heap-based buffer overflow triggered by a negative array index during the rsync protocol execution, specifically when the remote client acts as the receiver in a file transfer operation. The vulnerability exists in the memory management handling of rsync's data processing routines where insufficient bounds checking allows malicious input to cause memory access violations that can lead to arbitrary code execution or system instability.
The technical exploitation of this vulnerability requires a malicious client to have at least read access permissions to the target rsync module, establishing a prerequisite that aligns with common privilege escalation attack patterns. The negative array index condition suggests that the rsync implementation fails to properly validate array indexing parameters during protocol data parsing, particularly when handling file metadata or transfer parameters sent by remote clients. This type of vulnerability falls under the CWE-129 weakness category, which specifically addresses improper validation of array indices, and can be classified as a buffer overflow condition that operates at the heap memory level rather than stack-based memory corruption.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to potentially enable remote code execution when the out-of-bounds read allows an attacker to manipulate memory contents or trigger exploitable conditions in the rsync process. Attackers could leverage this vulnerability to execute arbitrary code on systems running vulnerable versions of rsync, particularly those configured to allow remote access with read permissions. The attack surface is significant given rsync's widespread deployment across network infrastructure, backup systems, and file synchronization services where it operates as a daemon service. This vulnerability directly maps to the ATT&CK technique T1059.007 for Command and Scripting Interpreter, as successful exploitation could allow attackers to execute commands on affected systems through the compromised rsync service.
Mitigation strategies for CVE-2025-10158 should prioritize immediate patching of affected rsync implementations with the vendor-provided security updates that address the array index validation flaw. System administrators should implement network segmentation and access control measures to limit rsync module access to trusted clients only, reducing the attack surface for potential exploitation. The principle of least privilege should be enforced by configuring rsync modules with minimal necessary permissions and disabling unnecessary features such as anonymous access or weak authentication mechanisms. Additionally, monitoring and logging of rsync operations should be enhanced to detect anomalous client behavior patterns that might indicate exploitation attempts, particularly around file transfer operations involving unusual data sequences or protocol deviations. Regular security assessments of rsync configurations should be conducted to identify and remediate potential privilege escalation vectors that could be leveraged to gain access to the vulnerable rsync service.