CVE-2025-34520: Arcserve UDP < 10.2 Authentication Bypass

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-08-27 · updated 2026-09-26
Weakness: CWE-288

Description

An authentication bypass vulnerability in Arcserve Unified Data Protection (UDP) allows unauthenticated attackers to gain unauthorized access to protected functionality or user accounts. By manipulating specific request parameters or exploiting a logic flaw, an attacker can bypass login mechanisms without valid credentials and access administrator-level features. This vulnerability affects all UDP versions prior to 10.2. UDP 10.2 includes the necessary patches and requires no action. Versions 8.0 through 10.1 are supported and require either patch application or upgrade to 10.2. Versions 7.x and earlier are unsupported or out of maintenance and must be upgraded to 10.2 to remediate the issue.

Affected products

Arcserve Unified Data Protection (UDP): before 7.0; from 8.0 before 10.2; 7.0, 7.0-update_1, 7.0-update_2 — fixed in 10.2, 7.0

How to fix

Upgrade to a fixed version: Arcserve Unified Data Protection (UDP) 10.2, 7.0. Check the vendor advisory for mitigations.

References

https://support.arcserve.com/s/article/Important-Security-Bulletin-Must-read-for-all-Arcserve-UDP-customers-on-all-versions

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