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

Severity: critical (CVSS 9.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-08 · updated 2026-07-24
Weakness: CWE-79

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.

Affected products

gitroomhq postiz-app: 2.21.6

References

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

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