Low

Stored HTML Injection in Nozomi Guardian/CMC Time Machine Snapshot Diff

IdentifiersCVE-2025-40891CWE-79· Improper Neutralization of Input…

CVE-2025-40891 is a stored HTML injection vulnerability in the Time Machine Snapshot Diff functionality of Nozomi Guardian/CMC, including affected Siemens RUGGEDCOM APE1808 deployments. The issue is caused by improper validation of network traffic data used to populate asset attributes. An unauthenticated attacker can send specially crafted network packets at two different times so that malicious HTML tags are stored across two snapshots. When a victim later uses the Time Machine Snapshot Diff feature on those specific snapshots and performs the required GUI actions, the injected HTML is rendered in the victim’s browser. According to the advisory, existing input validation and Content Security Policy prevent full JavaScript-based XSS exploitation, but HTML injection remains possible.

For your environment

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an attacker to cause attacker-controlled HTML to render in a victim user’s browser during Snapshot Diff operations. The stated impact is limited to phishing and open redirect style attacks, with limited confidentiality and integrity impact reflected in the advisory. Full XSS execution is reported as prevented by existing input validation and Content Security Policy, and no direct availability impact is described.

Mitigation

If you can’t patch tonight, do this now.

Until fixes are available, Siemens recommends protecting network access to affected devices and configuring deployments according to Siemens operational guidelines for Industrial Security. CISA additionally recommends minimizing internet exposure of control system devices, isolating control networks behind firewalls, segmenting control systems from business networks, and using secure remote access methods such as fully updated VPNs.

Remediation

Patch, then assume compromise.

Siemens states that fixes are being prepared and advises customers to contact customer support to obtain patch and update information for affected products. Apply vendor-provided updates as soon as they become available.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

Nozomi NetworksCmcapplication

Nozomi NetworksGuardianapplication

NozominetworksCmcapplication

NozominetworksGuardianapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

5 sources tracked across advisories and community write-ups. News coverage will land here when it surfaces.

5 SOURCESView more in app

No news coverage yet. Advisories and community discussion only.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity3