CVE-2026-45232
Description
A flaw was found in rsync. A network attacker can exploit an off-by-one out-of-bounds stack write vulnerability in the establish_proxy_connection() function by sending a malformed HTTP proxy response. This occurs when the RSYNC_PROXY environment variable is set and the attacker sends a response line of 1023 or more bytes without a newline terminator. This can corrupt stack memory, potentially leading to a Denial of Service (DoS).
Mitigation
To mitigate this issue, ensure that the `RSYNC_PROXY` environment variable is not set. If rsync is configured to use an HTTP proxy via this variable, unsetting it will prevent exploitation. To unset the `RSYNC_PROXY` environment variable for the current session, use: `unset RSYNC_PROXY`. For a more permanent solution, ensure that `RSYNC_PROXY` is not defined in system-wide or user-specific environment configuration files. Note that this mitigation will disable rsync's ability to use an HTTP proxy, which may impact functionality if proxy usage is required.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.9 | 3.7 | 3.1 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | High | High |
| Privileges Required | None | None | None |
| User Interaction | None | None | Required |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | None |
| Integrity Impact | None | None | None |
| Availability Impact | High | Low | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Instability
This weakness will generally lead to undefined behavior and therefore crashes. In the case of overflows involving loop index variables, the likelihood of infinite loops is also high.
Integrity
Technical Impact: Modify Memory
If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the wrap around results in other conditions such as buffer overflows, further memory corruption may occur.
Confidentiality,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism
This weakness can sometimes trigger buffer overflows which can be used to execute arbitrary code. This is usually outside the scope of a program's implicit security policy.
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