Medium [CVE-2026-53794] Denial of Service via --max-alloc=0 logic error
This medium-severity Red Hat Linux advisory covers CVE-2026-53794 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4.
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Summary
rsync before 3.5.0 contains a logic error in --max-alloc handling that allows a sender or configuration setting --max-alloc=0 to disable allocation sanity checks entirely rather than enforcing a zero-byte cap.
Attackers can exploit this flaw to cause the receiver to attempt unbounded memory allocations for file list and data structures, potentially exhausting available memory and causing a denial of service. A flaw was found in rsync.
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.
Red Hat severity: Moderate — CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L). Weakness: CWE-770.
Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9; Red Hat OpenShift Container Platform 4. Red Hat lists Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8 as not affected.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: rsync.
- < 3.5.0
Official advisory · high-confidence parse· fetched 12 minutes ago·verify at source
- 3.5.0
Official advisory · high-confidence parse· fetched 12 minutes ago·verify at source
Mitigation checklist
- 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.
Official advisory · high-confidence parse· fetched 12 minutes ago·verify at source
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