CVE-2026-43618
Analyzed Analyzed - Analysis Complete
Integer Overflow in Rsync Leading to Memory Disclosure

Publication date: 2026-05-20

Last updated on: 2026-05-21

Assigner: VulnCheck

Description
Rsync version 3.4.2 and prior contain an integer overflow vulnerability in the compressed-token decoder where a 32-bit signed counter is not checked for overflow, allowing a malicious sender to trigger an overflow that causes the receiver process to read and return data from outside the intended buffer bounds. Attackers can exploit this vulnerability to disclose process memory contents including environment variables, passwords, heap and stack data, and library memory pointers, significantly reducing ASLR effectiveness and facilitating further exploitation.
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Meta Information
Published
2026-05-20
Last Modified
2026-05-21
Generated
2026-06-09
AI Q&A
2026-05-20
EPSS Evaluated
2026-06-08
NVD
CVE-2026-43618
EUVD
EUVD-2026-31011
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
samba rsync to 3.4.2 (inc)
Helpful Resources
Exploitability
CWE
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KEV
KEV Icon
CWE ID Description
CWE-125 The product reads data past the end, or before the beginning, of the intended buffer.
CWE-190 The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
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Executive Summary

CVE-2026-43618 is an integer overflow vulnerability in rsync versions prior to 3.4.3, specifically in the compressed-token decoder. The problem arises because a 32-bit signed counter is incremented without proper overflow checks. A malicious sender can exploit this flaw to trigger an overflow, causing the receiver process to read and return data from outside the intended buffer bounds.

This unintended memory read can disclose sensitive process memory contents such as environment variables, passwords, heap and stack data, and library memory pointers.

The vulnerability reduces the effectiveness of Address Space Layout Randomization (ASLR), which is a security technique used to prevent exploitation, thereby facilitating further attacks.

Impact Analysis

Exploitation of this vulnerability can lead to disclosure of sensitive information from the affected system's memory, including environment variables, passwords, and memory pointers.

This information leakage significantly weakens security defenses such as ASLR, making it easier for attackers to carry out further exploits.

The vulnerability impacts confidentiality by exposing sensitive data, and it also affects availability and integrity as indicated by the CVSS score.

Detection Guidance

This vulnerability affects rsync versions prior to 3.4.3. To detect if your system is vulnerable, you can check the installed rsync version.

  • Run the command: rsync --version

If the version is 3.4.2 or earlier, your system is vulnerable to CVE-2026-43618.

Additionally, monitoring network traffic for rsync sessions that use compression might help identify potential exploitation attempts, since the vulnerability is in the compressed-token decoder.

Mitigation Strategies

The primary mitigation is to upgrade rsync to version 3.4.3 or later, where this vulnerability has been patched.

If upgrading immediately is not possible, a recommended workaround is to disable compression in the rsync daemon configuration to prevent exploitation of the compressed-token decoder.

Compliance Impact

This vulnerability allows attackers to disclose sensitive process memory contents including environment variables, passwords, and other memory data. Such unauthorized disclosure of sensitive information can lead to violations of data protection regulations like GDPR and HIPAA, which mandate the protection of personal and sensitive data.

By significantly reducing the effectiveness of Address Space Layout Randomization (ASLR) and facilitating further exploitation, this vulnerability increases the risk of data breaches and unauthorized access, which are critical compliance concerns under these standards.

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