CVE-2025-34521Network attack vector

Browser script execution via reflected unsanitized input

Published Aug 27, 2025 · Updated May 15, 2026

Reflected XSS in Arcserve Unified Data Protection (UDP) before 10.2 allows remote authenticated users to execute JavaScript in a victim's browser. The web interface's response-rendering logic reflects unsanitized user input into HTTP responses, so crafted links place attacker-controlled script in the page. A low-privileged account and a victim who follows the link in a shared browser context are required; successful execution exposes sessions and credentials.

CVSS severity4.8
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Arcserve Unified Data Protection (UDP) before 10.2 allows remote authenticated users to execute JavaScript in a victim's browser. The web interface's response-rendering logic reflects unsanitized user input into HTTP responses, so crafted links place attacker-controlled script in the page. A low-privileged account and a victim who follows the link in a shared browser context are required; successful execution exposes sessions and credentials.

The record

CVE
CVE-2025-34521
Published
Aug 27, 2025
Updated
May 15, 2026
Vendor
Arcserve
Product
Arcserve Unified Data Protection (UDP)
Classifications
CWE-79, CAPEC-591, T1204.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 27, 2025CVE publishedPublication date reported by the CVE source.
  2. May 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=7.*
  2. Affected versionversion=8.0 <=10.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Arcserve · Arcserve Unified Data Protection (UDP)version=0 <=7.*; version=8.0 <=10.1

Published CVSS scores

5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
4.8VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting')
CAPEC-591Reflected XSS
T1204.001User Execution: Malicious Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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