XSS in Gitroom Postiz
CVE-2026-42556
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.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.9 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L.
EPSS exploit prediction
EPSS: 0.003 (17.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 17.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Gitroom Postiz — versions 2.21.6
- Gitroomhq Postiz-App — versions >= 2.21.6, < 2.21.7
Weakness classification (CWE)
References
- github.com/gitroomhq/postiz-app/security/advisories/GHSA-hhxq-3wg7-4rj8 (Vendor Advisory)
- github.com/gitroomhq/postiz-app/releases/tag/v2.21.7 (Product, Release Notes)
Frequently asked questions
- What is CVE-2026-42556?
- CVE-2026-42556 is a high-severity vulnerability in Gitroom Postiz, classified under Cross-site Scripting. CVSS score: 8.9/10. Published 2026-05-08.
- How severe is CVE-2026-42556?
- High severity. CVSS v3 base score is 8.9 out of 10.