CVE-2026-45232: Off-by-one Error in RsyncProject rsync
Rsync versions before 3.4.3 contain an off-by-one out-of-bounds stack write vulnerability in the establish_proxy_connection() function in socket.c that allows network attackers to corrupt stack memory by sending a malformed HTTP proxy response. Attackers can exploit this by positioning themselves between the client and proxy or controlling the proxy server to send a response line of 1023 or more bytes without a newline terminator, causing a null byte to be written to an out-of-bounds stack address when the RSYNC_PROXY environment variable is set.
AI Analysis
Technical Summary
CVE-2026-45232 is an off-by-one out-of-bounds stack write vulnerability in Rsync versions before 3.4.3, specifically in the establish_proxy_connection() function within socket.c. The issue arises when a network attacker, positioned between the client and proxy or controlling the proxy server, sends a malformed HTTP proxy response line of 1023 or more bytes without a newline terminator. If the RSYNC_PROXY environment variable is set, this causes Rsync to write a null byte beyond the stack buffer boundary, potentially corrupting stack memory.
Potential Impact
The vulnerability allows remote attackers to corrupt stack memory by sending a specially crafted HTTP proxy response. However, exploitation requires the attacker to be able to intercept or control the proxy communication and the RSYNC_PROXY environment variable to be set. The CVSS 4.0 base score is low (2.1), indicating limited impact and exploitability. There are no known exploits in the wild.
Mitigation Recommendations
No official patch or remediation level is currently documented. Users should upgrade to Rsync version 3.4.3 or later once available, as this version is indicated as the fixed version. Until then, avoid setting the RSYNC_PROXY environment variable or ensure that proxy responses are properly validated and controlled to prevent malformed responses. Monitor vendor advisories for updates regarding an official fix.
CVE-2026-45232: Off-by-one Error in RsyncProject rsync
Description
Rsync versions before 3.4.3 contain an off-by-one out-of-bounds stack write vulnerability in the establish_proxy_connection() function in socket.c that allows network attackers to corrupt stack memory by sending a malformed HTTP proxy response. Attackers can exploit this by positioning themselves between the client and proxy or controlling the proxy server to send a response line of 1023 or more bytes without a newline terminator, causing a null byte to be written to an out-of-bounds stack address when the RSYNC_PROXY environment variable is set.
CVSS v4.0
Score 2.1low
Affected software
pkg:github/rsyncproject/rsyncRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-45232 is an off-by-one out-of-bounds stack write vulnerability in Rsync versions before 3.4.3, specifically in the establish_proxy_connection() function within socket.c. The issue arises when a network attacker, positioned between the client and proxy or controlling the proxy server, sends a malformed HTTP proxy response line of 1023 or more bytes without a newline terminator. If the RSYNC_PROXY environment variable is set, this causes Rsync to write a null byte beyond the stack buffer boundary, potentially corrupting stack memory.
Potential Impact
The vulnerability allows remote attackers to corrupt stack memory by sending a specially crafted HTTP proxy response. However, exploitation requires the attacker to be able to intercept or control the proxy communication and the RSYNC_PROXY environment variable to be set. The CVSS 4.0 base score is low (2.1), indicating limited impact and exploitability. There are no known exploits in the wild.
Mitigation Recommendations
No official patch or remediation level is currently documented. Users should upgrade to Rsync version 3.4.3 or later once available, as this version is indicated as the fixed version. Until then, avoid setting the RSYNC_PROXY environment variable or ensure that proxy responses are properly validated and controlled to prevent malformed responses. Monitor vendor advisories for updates regarding an official fix.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-05-11T14:14:49.612Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a0d0f6cba1db473621796e9
Added to database: 05/20/2026, 01:33:32 UTC
Last enriched: 07/15/2026, 10:01:39 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 76
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