CVE-2026-40487
Gitroom Postiz unrestricted file upload
- Published18 Apr 2026
Description
Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypass allows any authenticated user to upload arbitrary HTML, SVG, or other executable file types to the server by spoofing the `Content-Type` header. The uploaded files are then served by nginx with a Content-Type derived from their original extension (`text/html`, `image/svg+xml`), enabling Stored Cross-Site Scripting (XSS) in the context of the application's origin. This can lead to session riding, account takeover, and full compromise of other users' accounts. Version 2.21.6 contains a fix.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:LAffected products
Remediation
References
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2026-40487 being actively exploited?
CVE-2026-40487 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.26%.
How severe is CVE-2026-40487?
CVE-2026-40487 has a CVSS 3.1 base score of 8.9, rated high. EPSS estimates a 0.26% probability of exploitation.
Which products are affected by CVE-2026-40487?
Affected products include Gitroom Postiz.
How do I fix CVE-2026-40487?
Upgrade affected software to a fixed version, for example Gitroom Postiz 2.21.6 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-40487 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.