Stack corruption via HTTP proxy response parsing
Published May 20, 2026 · Updated May 20, 2026
Out-of-bounds write in rsync before 3.4.3 allows man-in-the-middle attackers to corrupt client stack memory via an HTTP proxy response. The establish_proxy_connection() handler in socket.c checks an unwritten buffer slot after a 1023-byte newline-free response, increments past the 1024-byte array, and writes a null byte out of bounds. Reachability requires client use of RSYNC_PROXY and a malicious proxy or network position before it; the fixed-offset null write can cause client misbehavior or a later crash but is not an arbitrary-write primitive.
Summary
What happened
Out-of-bounds write in rsync before 3.4.3 allows man-in-the-middle attackers to corrupt client stack memory via an HTTP proxy response. The establish_proxy_connection() handler in socket.c checks an unwritten buffer slot after a 1023-byte newline-free response, increments past the 1024-byte array, and writes a null byte out of bounds. Reachability requires client use of RSYNC_PROXY and a malicious proxy or network position before it; the fixed-offset null write can cause client misbehavior or a later crash but is not an arbitrary-write primitive.
The record
- CVE
- CVE-2026-45232
- Published
- May 20, 2026
- Updated
- May 20, 2026
- Vendor
- Rsync Project
- Product
- rsync
- Classifications
- CWE-457, CWE-193, CWE-787, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 20, 2026CVE publishedPublication date reported by the CVE source.
- 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.
- Affected versionversion=0 <3.4.3
What conditions does exploitation require?
What is affected?
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.
Weakness, pattern, technique
Public exploit references
- proxy-response-line-too-long regression testproof of concept · demonstrated
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Technologies
Your stack
See the directory against your own environment.
Your stack
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