CVE-2025-40891

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.

CVSS v3.1 Score

4.7

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

Affected Products

Vendor	Product	Versions
nozominetworks	cmc	< 25.5.0
nozominetworks	guardian	< 25.5.0

References

Advisories & Patches

https://security.nozominetworks.com/NN-2025:12-01

Other References

https://cert-portal.siemens.com/productcert/html/ssa-827968.html

Frequently Asked Questions

What is CVE-2025-40891? +

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. It has a CVSS v3.1 base score of 4.7 (MEDIUM).

How severe is CVE-2025-40891? +

CVE-2025-40891 has a CVSS v3.1 score of 4.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-40891? +

CVE-2025-40891 affects products from nozominetworks, specifically: cmc, guardian. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-40891? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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