Rsync is a widely deployed core file-sync/backup daemon; this flaw lets attackers bypass host deny rules to access restricted file modules, risking data exposure and operational disruption across many systems.
CVE-2026-70452
rsync daemon DNS failures allow bypass of hostname deny rules enabling unauthorized access
Is CVE-2026-70452 being exploited?
Not confirmed. CVE-2026-70452 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.46% probability of exploitation in the next 30 days.
How severe is CVE-2026-70452?
CVE-2026-70452 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-70452?
Yes. A fix has been recorded for CVE-2026-70452. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-70452 affect?
CVE-2026-70452 affects rsync < 3.5.0 (rsyncd), Linux/Unix servers running rsync daemon, Backup and file-sync servers using hostname ACLs. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-70452?
Upgrade rsync to >=3.5.0; restrict rsyncd exposure; enforce DNS reliability and firewall ACLs
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attackers can induce DNS resolution failures to bypass hostname-based deny rules and access restricted rsync modules, enabling unauthorized read/write of files.
Immediate action required
- affected>= 3.1.0 and <= 3.4.4
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.