CVE-2026-42556 Postiz stored XSS in public preview page
Authenticated users can inject malicious HTML into post previews, leading to stored XSS and potential account takeover when victims view the link.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-42556?
CVE-2026-42556 is a high-severity cross-site scripting vulnerability in gitroomhq postiz-app, published on 8 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-42556?
It affects 1 product.
Products include Gitroom Postiz.
How do I fix CVE-2026-42556?
No fix has been published for CVE-2026-42556 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-42556 being exploited?
There is no known exploitation of CVE-2026-42556 in the wild and no public exploit code.
Other vulnerabilities in gitroomhq postiz-app
- CVE-2026-42298 Postiz: Arbitrary Code Execution and Token Exfiltration in pr-docker-build.yml via untrusted Dockerfile.dev
- CVE-2026-40487 Postiz Has Unrestricted File Upload via MIME Type Spoofing that Leads to Stored XSS
- CVE-2026-34577 Postiz: Unauthenticated Full-Read SSRF via /public/stream Endpoint with Trivially Bypassable Extension Check
- CVE-2026-34576 Postiz: SSRF in upload-from-url endpoint allows fetching internal resources and cloud metadata
- CVE-2026-40168 Postiz has Server-Side Request Forgery via Redirect Bypass in /api/public/stream
Sources
Also known as GHSA-hhxq-3wg7-4rj8.