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OpenAdvisories
Medium · 4.7 CVE-2025-40891 EUVD-2025-204261GHSA-q3xp-m695-72w5

HTML injection in in Time Machine functionality in Guardian/CMC before 25.5.0

Published Dec 18, 2025 · Updated Aug 11, 2026 · Assigned by Nozomi

Description

A Stored HTML Injection vulnerability was discovered in the Time Machine Snapshot Diff functionality due to improper validation of network traffic data. An unauthenticated attacker can send specially crafted network packets at two different times to inject HTML tags into asset attributes across two snapshots. Exploitation requires a victim to use the Time Machine Snapshot Diff feature on those specific snapshots and perform specific GUI actions, at which point the injected HTML renders in their browser, enabling phishing and open redirect attacks. Full XSS exploitation is prevented by input validation and Content Security Policy. Attack complexity is high due to multiple required conditions.

Affected products

VendorProductAffectedFixed
Nozomi Networks Guardian < 25.5.0 25.5.0
Nozomi Networks CMC < 25.5.0 25.5.0

Advisories 3

References