CVE-2026-53794
Description
A flaw was found in rsync. A logic error in the --max-alloc handling allows a remote attacker to disable memory allocation sanity checks by setting --max-alloc=0. This can lead to the receiver attempting unbounded memory allocations, potentially exhausting available memory and causing a denial of service.
Statement
This vulnerability in rsync is rated as Important. A remote attacker can exploit a logic error in the --max-alloc handling by providing --max-alloc=0, which disables memory allocation sanity checks. This can lead to unbounded memory consumption on the receiving system, resulting in a denial of service without requiring authentication or user interaction. Red Hat systems using rsync, particularly in daemon mode or when processing untrusted data, are at risk.
Mitigation
Avoid using the `--max-alloc=0` option in rsync configurations or command-line arguments. If rsync is operating as a daemon, ensure that its configuration does not include `--max-alloc=0`. For rsync clients, refrain from using `--max-alloc=0` when synchronizing with untrusted sources. This mitigation prevents the disabling of memory allocation sanity checks, thereby avoiding unbounded memory consumption. If rsync is running as a service, a restart may be required for configuration changes to take effect.
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 | 5.3 | N/A | 5.3 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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