---
id: CVE-2025-40891
title: >-
  A Stored HTML Injection vulnerability was discovered in the Time Machine
  Snapshot Diff functionality due to improper validation of network traffic data
summary: >-
  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 differ…
severity: medium
cvss: 4.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N'
cwe:
  - CWE-79
vendor: nozominetworks
product: cmc
affected:
  - cmc < 25.5.0
  - guardian < 25.5.0
patched:
  - cmc 25.5.0
  - guardian 25.5.0
published: '2025-12-18'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T23:10:00.237'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-40891'
references:
  - url: 'https://security.nozominetworks.com/NN-2025:12-01'
    label: prodsec@nozominetworks.com
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-827968.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.00176
epssPercentile: 0.06468
ingestedAt: '2026-09-30T23:29:32.503Z'
---

## Overview

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

- `cmc < 25.5.0`
- `guardian < 25.5.0`

## Remediation

Upgrade past the affected range:

- `cmc 25.5.0`
- `guardian 25.5.0`